tonight, labor day blitz. 2016 candidates campaigning on overdrive this holiday as joe biden hears cheers of "run, joe, run" and hillary clinton gets some of her worst polling news yet. opening the gates. a number of countries committing to giving refuge to tens of thousands in search of freedom. as the masses keep coming, flooding the borders. breaking his silence. an american dentist says he's ready to go back to his life and his business after getting threats for killing a beloved lion in africa. and the ancient mystery of stonehenge goes beyond what we thought we knew. a new discovery showing the famous site may be only a piece of a much larger puzzle. "nightly news" begins right now.

>> announcer: from nbc news world headquarters in new york, this is "nbc nightly news with lester holt." good evening on this labor day. i'm kate snow, in for lester holt. and it's been a busy day on the picnics and parade political circuit from iowa to new hampshire to pennsylvania. 2016 candidates took advantage of this holiday to meet with voters with at least a few voices in the crowd at pittsburgh's annual parade urging the vice president to throw his hat into the ring. chants of "run, joe, run" popped up as he marched by. in iowa hillary clinton called all the talk about her e-mails a distraction and said the issue hasn't affected her as a candidate much. nbc's kristen welker has it all covered tonight from iowa. >> reporter: a crush of candidates this labor day crashing picnics, parading the streets, diving into crowds, courting voters every way they can. a crucial moment for hillary clinton,

making three stops in and around iowa today, a state she lost to barack obama in 2008. >> can you do a selfie? >> reporter: there are signs she's in trouble here again. according to the latest nbc news/marist poll, vermont senator bernie sanders has cut clinton's lead to just 11 points, down from 29 in july. and in new hampshire sanders has snatched the lead from clinton, now topping her 49% to 38%. >> it feels great. and i think we have, as you can see here today, a lot of support in new hampshire. >> reporter: one factor in clinton's drop, persistent questions about her e-mails. still again today in an interview with the associated press, she insisted everything she did was allowed and she has nothing to apologize for. over the weekend clinton acknowledged personally paying a state department staffer brian pagliano to maintain her private e-mail server while she was secretary. this after pagliano said he will plead the fifth about his involvement. >> we have encouraged everyone to cooperate. >> reporter: today

clinton tried to pivot back to her campaign message. >> i believe i've got the vision, the policies, the skill, the tenacity and the determination to get us back on the right track. >> reporter: with clinton trying to right her campaign, a seemingly carefree vice president joe biden marched with organized labor in pittsburgh. and again supporters encouraged him to run. >> i've got it talk to my wife about that. >> reporter: further fueling speculation about a biden campaign, the new poll numbers in iowa show while donald trump beats clinton here 48-43, biden topped the republican front-runner 49%. but even if he jumps out voters clearly prefer washington outsiders. that's you why see sanders surging as well as business executive carly fiorina who today said it's about electing a different kind of leader. kate? >> kristen welker in davenport, iowa. i want to turn to cnbc's chief

washington correspondent john harwood. john, it's the unofficial end of summer today. it is also the unofficial start of the serious campaign season, right? >> kate, it's a little like pro football. the preseason games only tell you so much. now the campaigns begin to spend real money on ads and engage each other more directly and voters begin looking more critically at potential presidents. those factors will start to tell us among other things whether donald trump is a political entertainer or running to win, whether jeb bush can turn around, become the more powerful candidate that we once expected. on the democratic side hillary clinton could benefit from a faster-paced campaign if it diminishes the focus on her e-mails. but she faces two big variables in addition to a surprisingly effective challenge from bernie sanders. one is the decision by vice president biden on whether to run against her. the other is her public testimony in october before the house committee investigating the benghazi attacks. final wild card comes this month when president obama and congress face off over funding the government. republican leaders say they want to avoid a

crisis, but as we've seen in washington and on the campaign trail, kate, their ability to do that is limited. >> john harwood, game on. thanks so much. with the stroke of the president's pen on this labor day, about 300,000 workers will get something many have fought for -- guaranteed paid sick leave. president obama announced an executive order giving sick leave to employees of federal contractors, among others. starting in 2017 they'll get up to seven sick days a year, depending on how many hours they work. overseas tonight, hundreds have broken through police lines in hungary, impatient with that country's handling of the refugee crisis. europe's leaders are arguing over what to do with all those people. some countries are rounding them up. some now hesitantly offering help. others like germany officially welcoming them. we have reports from hungary and germany tonight, starting with our chief foreign correspondent richard engel at the hungarian border again tonight. richard, good evening. >> reporter: good evening, kate.

frustration is growing among the refugees and migrants because hungary is detaining them but doesn't even have a place to put them. this is a spillover area where families are sleeping outside one of the camps. which is filled to capacity. the river of migrants and refugees streaming into europe and specifically toward germany is overflowing. and eastern european governments have shown little interest in taking them. especially hungary. hungarian media report there are about 50,000 migrants in the country right now, and police are trying to take control of them and round them up. the government seems to be treating this more like an invasion than a migration of desperate people. we watched as hungarian police encircled one group for hours. camps here are full. so families are simply being left outside. no shelter but under guard. children like miriana, 5 years old, from syria. like many here,

yettia, another syrian, told us the treatment was humiliating and unnecessary, they weren't being violent. "there isn't one person here who hasn't lost a relative. why don't they treat us with dignity," he asked. europe can't agree on what to do with yettia or miriana or the thousands of others arriving every day. european leaders today proposed a controversial solution, resettlement quotas. germany would take in 40,000 refugees. france 24,000. and the uk, until now the most reluctant of the great european powers, is opening up its doors wider too. >> so mr. speaker, we are proposing that britain should resettle up to 20,000 syrian refugees overt rest of this parliament. in doing so we'll continue to show the world that this country is a country of extraordinary compassion. >> reporter: extraordinary perhaps but enough?

there are millions from syria, iraq, and afghanistan who want to leave their war zones. richard engel, nbc news, hungary. >> reporter: i'm kelly cobiella in munich, where hundreds of refugees arrive at the city's main train station every hour. exhausted and relieved. >> bravo! >> reporter: ordinary germans cheer each new group. a warm welcome op a cold day. >> actually, i'm very thankful. >> reporter: it's taken university students mohammed dor-it and basel kunkit 25 days to get here. both are from syria and left war and families behind. mohammed wants to bring his 9-month-old daughter here but not the way he came. hundreds of children like this are pouring into germany. they've survived dangerous seas and hostile countries. now they have candy. toys. and medical care if they need it. more than 20,000 migrants and refugees have arrived here over

the past three days. here they're given food and warm clothing and then they board buses for shelters across germany. from frankfurt to berlin it's friendly and efficient, a welcoming party, a family meal, and a place to sleep. the only trouble spot -- small fires that broke out at two refugee shelters overnight. several were hurt, and police are investigating both as arson. but scenes like this are far more common. nearly everyone, it seems, wants to help. >> because i'm a human being and that are humans and if you see the situation you can't do anything but come here. >> reporter: germany endeavoring for now at least to set an example for europe and the world. even at this late hour there are long lines of refugees waiting to board buses at the train station behind me. the flow of refugees and migrants here certainly slowed since

the weekend. but kate, it shows no sign of stopping. kate? >> kelly cobiella, so powerful to see all that. thank you so much. back in this country, attorneys for the kentucky county clerk jailed for refusing to issue marriage licenses to same-sex couples have filed an emergency motion to bring her case before the governor. her appeal is pending. kim davis wants an exception based on her religious beliefs. an american dentist who became the target of protests has decided to come out from the shadows. months after he hunted and killed a beloved lie lion in zimbabwe walter palmer is breaking his silence and planning to return to work despite threats against his family and him. our stephanie gosk has the latest details. >> justice for cecil! >> reporter: after being publicly named and shamed for killing cecil the lion, minnesota dentist dr. walter palmer dropped out of sight. his dental office was shuttered for weeks because of protests.

now as the big game hunter prepares to return to his minnesota practice, he's speaking out. "if i had known this lion had a name and was important to the country or a study, obviously i wouldn't have taken it." in an interview with the minneapolis star tribune and the associated press, dr. palmer said the hunt in zimbabwe was perfectly legal and he is heartbroken about the disruption this has caused his staff. the 55-year-old, who has not been charged with a crime, also intains that he has not been in hiding. "i've been out of the public eye. that doesn't mean i'm in hiding." cecil the lion was killed outside of the park grounds where he lived and was protected. when dr. palmer was named by zimbabwe officials in late july, it triggered an instant backlash. television host jimmy kimmel gave this emotional monologue. >> people loved to see him on safaris until earlier this month when a tourist on a hunting trip shot him. >> reporter: petitions

circulated to extradite dr. palmer to zimbabwe. his vacation home was vandalized. "this has been especially hard on my wife and my daughter. they've been threatened in the social media. and again, i don't understand that level of humanity, to come after people not involved at all." asked whether he would ever return to zimbabwe for future hunts, dr. palmer said he didn't know. stephanie gosk, nbc news. still ahead tonight, the parents on a mission to keep others from dying the way their daughter did, by finding a way to alert car owners about safety defects even before the vehicles are recalled. special olympics has almost five million athletes in 170 countries. the microsoft cloud allows us to immediately be able to access information, wherever we are. information for an athlete's medical care, or information to track their personal best. with microsoft cloud, we save millions of man hours, and that's time that we can invest in our athletes and

changing the world. as we age, certain nutrients... longer than ever. ...become especially important. from the makers of one a day fifty-plus. new one a day proactive sixty-five plus. with high potency vitamin b12... ...and more vitamin d. ♪ hi, tom. how's the college visit? does it make the short list? yeah, i'm afraid so. it's okay. this is what we've been planning for. knowing our clients personally is why edward jones is the big company that doesn't act that way.

try phillips' fiber good gummies plus energy support. it's a new fiber supplement that helps support regularity and includes b vitamins to help convert food to energy. mmmmm, these are good! nice work, phillips! the tasty side of fiber, from phillips'. i was out for a bike ride. i didn't think i'd have a heart attack. but i did. i'm mike, and i'm very much alive. now my doctor recommends a bayer aspirin regimen to help prevent another heart attack. be sure to talk to your doctor before you begin an aspirin regimen.

we're back now with an nbc news investigation. think of the lives that could be saved if you could find out about a safety defect in your car before it's recalled. that's the goal of a couple whose daughter was killed in a gm car that was later part of a massive recall. they're using the proceeds from their claims against gm to fund the creation of a new vehicle safety watch list. nbc's tom costello reports on what they've found. >> reporter: the gm recall massive. 2.6 million vehicles. ignition switches that could shut off while the car was running. air bags that would not deplay in an accident. in all, hundreds of injuries, and 124 death claims settled, including 29-year-old brooke melton, who died in 2010. >> on her deathbed after i kissed her on the forehead, told her i loved her, i told her i would vindicate

her death. >> reporter: it was the meltons' lawsuit that helped prove gm knew of the effective ignition switch for years yet failed to act. now the meltons are determined to help flag potential safety problems that may deserve a closer look. funding a vehicle safety watch list that gathers raw government data from all 50 states, then looks for trends in death and injury claims. >> it's a way to prioritize how to examine potential vehicle safety defects before they become crises. >> reporter: already they believe they've identified a potential steering problem with a top-selling car that deserves a closer look. the 2012 ford focus. more than 300,000 sold in the u.s. government records show more than 100 complaints about a sudden failure of its power steering like it's unsafe to drive and "i love complete control of the vehicle." >> i was scared. yeah. it locked up on me, and i couldn't turn the steering well at all. >> reporter: amy and mike kamara say it

happened while amy was driving 50 miles per hour on a florida highway. >> we're not alone in this. there's many, many, many people that are in the same boat we are right now. >> reporter: the national highway traffic safety administration, or nhtsa, hasn't launched a formal investigation. nhtsa has been under fire recently for failing to quickly identify safety issues and order recalls. in june an inspector general report found weaknesses in nhtsa's oversight have resulted in significant safety concerns being overlooked. the secretary of transportation says he's aware of the new watch list and the ford focus complaints. >> is this something that you will be looking at? >> it is being looked at, yes. >> any potential enforcement action? >> we'll see. we go where the facts lead us. >> reporter: in may ford recalled more than 400,000 other models for an electrical problem that it said could result in a loss of power steering. ford tells nbc news it's confident in its own methods for identifying safety issues and moves quickly to address them. as for the new watch list -- "we don't recognize the vehicle

safety watch list analytics methodology used for this report. we take the safety of our customers very seriously." meanwhile, the meltons say the new watch list is about honoring their daughter's memory. >> what we really hope is for other families to be able to use this information and prevent accidents. we think it can save lives. >> reporter: it's not yet clear whether the 2012 ford focus poses a risk. the meltons believe the owners deserve to know. tom costello, nbc news, washington. we're back in a moment with serena williams. will her quest for one of the most amazing feats in all of sports be derailed by her own sister? ♪

[ female announcer ] as katie puts her cellphone down for the first time all week, she realizes that stouffer's lasagna is topped with fresh cheese that browns beautifully. fresh cheese and a touch of aged parmesan is what gives us our irresistible flavor. [ cellphone buzzing ] what? [ female announcer ] when you start with the best blend of cheese, you get the best lasagna. stouffer's. made for you to love. nestle. good food, good life. wi noticed benny right away. , made for you to love. i just had to adopt him. he's older so he needs my help all day. when my back pain flared up we both felt it i took tylenol at first but i had to take 6 pills to get through the day. then my friend said "try aleve". just two pills, all day. and now, i'm back for my best bud!

aleve. all day strong and try aleve pm, now with an easy open cap. after wins this weekend the next chapter in one of the greatest sibling rivalries in all of sports will be written tomorrow, when serena and venus williams face off once again. they'll meet in the quarterfinals of the

u.s. open. serena is going for a calendar year grand slam, which hasn't been done in 27 years. serena leads venus in all-time matches against each other, 15-11. now to an incredible find overseas. an elaborate series of stone monuments believed to have been hidden for thousands of years not far from the famous site of stonehenge. and it suggests that mysteries that shroud this region are bigger than many of us even thought. nbc's jacob rascon has our story. >> reporter: the mystery of stonehenge has fascinated the world for centuries. every year more than 1 million tourists visit the site in southwest england that dates back more than 4,000 years. >> the whole area here is sort a neolithic -- well, minefield really, which is wonderful. >> reporter: for the last five years a team of archaeologists has been digging deeper using sophisticated ground radar. the archaeologists were finished, packing up, and ready to go. they did one final

survey, and made the most remarkable discovery of the entire study. three feet below the earth. >> reporter: this rendition shows the giant monument of as many as 100 stones, with space for 100 more. stones up to 15 feet tall and six feet wide, stretching nearly a mile in a c shape. scientists believe the formation, less than two miles from stonehenge, was likely built for the same purpose -- worship and rituals. archaeologists have made hundreds of additional discoveries around stonehenge but never this large. >> archaeologists have been coming to this landscape for the last 400 years, but this is the first time that we've ever really gotten a clue that there are a whole series of stones lying buried there, which is extraordinary. >> reporter: a new discovery prompting even more questions about one of the world's greatest puzzles. jacob rascon, nbc news, wiltshire,

england. and when we come back, come sail away on the journey where city slickers find their sea legs and so much more. it's easy to love your laxative when that lax loves your body back. only miralax hydrates, eases and softens to unblock naturally, so you have peace of mind from start to finish. love your laxative. miralax. it's tough, but i've managed. crohn's disease. but managing my symptoms was all i was doing. so when i finally told my doctor, he said humira is for adults like me who have tried other medications but still experience the symptoms of moderate to severe crohn's disease. and that in clinical studies, the majority of patients on humira saw significant symptom relief. and many achieved remission. humira can lower your ability to fight infections, including tuberculosis. serious, sometimes fatal infections and cancers, including lymphoma, have happened; as have blood, liver, and nervous system problems, serious allergic reactions, and new or worsening heart failure. before treatment, get tested for tb.

tell your doctor if you've been to areas where certain fungal infections are common, and if you've had tb, hepatitis b, are prone to infections, or have flu-like symptoms or sores. don't start humira if you have an infection. if you're still just managing your symptoms, ask your gastroenterologist about humira. with humira, remission is possible. you...and itchy eyes.more than sneezing... they also bring tough nasal congestion. so you need claritin-d. it starts to work... ...in just 30 minutes. in fact, nothing works faster. so blow away nasal congestion, fast, with claritin-d. your bladder is changing,se it doesn't mean that you have to. with tena let yourself go. be the one with the crazy laugh. and keep being their favorite playmate. with tena's unique

super-absorbent micro-beads that lock in moisture and odor. tena lets you be you. so you're a small business expert from at&t? yeah, give me a problem and i've got the solution. well, we have 30 years of customer records. our cloud can keep them safe and accessible anywhere. my drivers don't have time to fill out forms. tablets. keep it all digital. we're looking to double our deliveries. our fleet apps will find the fastest route. oh, and your boysenberry apple scones smell about done. ahh, you're good. i like to bake. add new business services with at&t and get up to $500 in total savings. before we say good-bye to summer we

have one last adventure this labor day. a crew of young women embarking on a voyage where teamwork is the only way to succeed. remarkably, just days before they didn't know the ropes or each other. here's harry smith. >> reporter: on a sleepy old sloop docked along the hudson river north of new york city its young crew is getting instructions. a lot of instructions. >> turn it back on itself. >> reporter: high schoolers from brooklyn, staten island, albany. >> heave, heave. >> reporter: being transformed from la landlubers to sea dogs in a program called young women at the helm. >> i thought it would be an amazing opportunity to see what it was like to be on a boat for real. and since like boys get to do everything it was nice that it was a girls' trip. >> reporter: along with sailing there's rigorous instruction in history, geography -- >> all of this land. >> reporter: -- and ecology, often taught by volunteers who

themselves were once newbies on the boat. >> it's not a little bit cool. it's like inexplicably cool. >> reporter: on-board educator maya nime sachlt to says it's an experience that can change lives. >> if you're at the helm of your life you're the one deciding what you're doing and where you're going. and they get the chance to stand at the helm of a 100-foot ship and decide where the boat is going. >> reporter: girls who had never sailed find themselves doing things they'd never dreamed of. >> i was pulling ropes on a boat. and i helped it move. and i steered on the tiller and i did a whole bunch of things. >> reporter: the clearwater was launched in 1969 by the late pete seeger in an effort to bring attention to the toxic state of the hudson. the river has gained new life, and the clearwater keeps moving those who board her. >> i want something better for myself. i want to explore much more than i already have. >> yeah. >> and this has really shown me that. >> reporter: maybe three days on the water won't make you a full-fledged mariner. but it could give you the confidence to be

the captain of your own life. harry smith, nbc news, beacon, new york. >> just beautiful. that will do it for us on this labor day evening. i'm kate snow. lester holt will be back tomorrow. for all of us at nbc news, thank you for watching. have a great night. i was about to head to thecheck. bank, but out of nowhere it just started to rain. like really rain.

[clap of thunder] i did not want to go out. [clap of thunder] but then i was like duh, just use your phone. mobile-deposit-techno-thingy to the rescue. i'm rayna. and i bank human at td bank. lights, camera, access. >> is it being played up for the cameras or is there an attraction? >> could you ever see it evolving into more than friends? >> just friends or something more? i'm liz hernandez with candice