. >> announcer: from nbc news world headquarters in new york, this is "nbc nightly news" with lester holt. to a lot of people, the republican race for president may be feeling more and more like a reality show tonight, starring a man that before he became a candidate, proved he could draw an audience. so donald trump will likely have a lot of eyeballs watching tonight. either the republican debate that he's now vowed to boycott or his own event that could steal the spotlight. leading up to this, a public duel with fox news that he reconsider. even primetime discussions of milkshakes. all just four days until the vote in iowa. nbc's peter alexander explains. >> reporter: tonight should be the republican's final iowa caucuses, instead, donald trump's no-show is stealing the the front-runner staging his own primetime event to raise money for veterans. going head-to-head on the fox news debate three miles away. even drawing his underdog opponents, like huckabee and santorum. >> you're not giving them -- away. defiantly positioning himself as the deal maker in chief. >> it's called an eye

"nightly news" begins right now. >> announcer: from nbc news world headquarters in new york, this is "nbc nightly news" with lester holt. >> good evening. for president may be feeling more and more like a reality show tonight starring a man who before he became a candidate, proved he could draw an audience. and so donald trump will likely have a lot of eyeballs watching tonight.t. either the republican debate that he has now vowed to boycott or his own event that could steal the spotlight. leading up to all this, a public dual with fox news, public pleas that he reconsider, even prime time discussions of milkshakes, all just four days until the vote in iowa. peter alexander explains. >> reporter: tonight should be the republicans final showdown before the wow caucuses. the front-runner staging his own prime time event to raise money for veterans. going head to head on tv with the fox news debate just three miles away. even drawing a pair of his underdog opponents. mike huckabee and rick santorum. >> by walking away from this debate -- i was pushed away. i'm not walking away. >> trump

erica hill, nbc news, new york. >>> and that will do it for us on this thursday night. i'm lester holt. from all of us at nbc news, thank you for

our nbc news investigation into the new > and recess time. we'll go to a school where the kids are getting a lot more "nightly news" begins now. >> announcer: this is nbc "nightly news" with kate snow. report tonight from h carolina. from the gilyard center where they're putting the final touches on the big stage behind in politics. the final democratic debate before the voting starts in iowa he just two weeks from our new nbc news "wall street journal" poll sets the stage. hillary clinton with a wide. 59% of democratic primary voters pick hillary clinton, bernie sanders at 34%, and martin t just 2%. but in hypothetical head-to-head match-ups with donald trump bernie sanders does better than hillith polls in iowa and new hampshire tightening over the past week there's a lot at stake here tonight. all while donald trump and tnue to battle it out on the trail. we have all of it covered. let's start out tonight with kristen welker is hrleston. kristen. >> reporter: kate evening. you can feel the anticipation building. officials with the clinton

. >>> an nbc news investigation revealing a replacement for a medical device associated with dozens of deaths also has potentially fatal flaws. "nightly news" begins right now. >>> good evening. the pictures were alarming. a towering hotel in dubai engulfed in flames. debris raining down on the streets below. the fire broke out just a couple of hours celebrations were planned to ring in the new year. despite the inferno, only minor injuries have been reported so far. at midnight, the city went on with a record-breaking fireworks display, creating a surreal scene. keir simmons has the dramatic pictures. coming from dubai tonight. >> reporter: flames 20 floors high engulf a luxury building. chunks of debris falling, still on fire. >> six or seven minutes the entire side of the building was engulfed in flames. >> reporter: more than two hours, dubai's skyline lit up and not by its scheduled fireworks display. emergency responders racing to help. >> we saw quite a bit of firefighters making their way running top speed through the mall. to try to get to that location. >> reporter: inside th

. >>> from nbc world headquarters in new york, this is nbc "nightly news." reporting tonight, erica hill. >>> good evening. in iowa tonight, it's a full court press. with the caucuses 48 hours away, candidates aren't wasting a moment, especially among the undecided. crisscrossing the state to make their final pitches, trying to meet as many voters as possible. in a poll tonight, hillary clinton is leading bernie sanders, 45 to 42% in iowa. a virtual dead heat for the democrats. donald trump may be leading among republicans, 28%. ted cruz, 23. and marco rubio, 15%. nbc news has full coverage. we begin in cedar rapids with kristen welker. >> reporter: secretary clinton will look for votes here. top surrogates, her husband and daughter chelsea. just a few miles away and in the exact same city, bernie sanders is making his final pitch in this race that is tight. hillary clinton and bernie sanders neck and neck, pulling out all the stops in the final hours before iowa voters weigh in. clinton facing new questions over her private e-mails. the state department rel

richard engel, nbc news, istanbul. >>> still ahead here tonight, what to do. new guidelines just out for breast cancer screening, different from other advice you've likely heard. what you should be >>> also, they are packing their trunks and headed for retirement. where ringling >>> the decision about when to start getting annual mammogram is one of the most controversial questions in women's health care. it is a issue we've covered extensively here on "nightly news." and tonight we have updated news that decision even more difficult. anne thompson reports on the new guidelines. >> reporter: the ever-shifting guidelines for starting mammograms leaves some women feel like they are playing a game of chess. age 40 and once a year said the american congress of onstet ises and gynocologists. 45 is american cancer. and 50 is from the u.s. preventative services task force. the government advisory panel said screening for women in their 40s could be affective but it is an individual decision. >> in 40s, we find the benefit is smaller. and that there are harms. >> the h

and tonight we have updated news that could make that decision even more difficult. nbc's anne thompson reports on the new guidelines. >> reporter: the ever-shifting guidelines for starting mammograms like they are playing a game of chess. age 40 and once a year said the american congress of obstetricians and gynecologists. 45 and yearly is what the american cancer society. .r.e.c.o.m.m.e.n.d.s. 50 and every two years is from the u.s. preventative services task force. the government advisory panel said screening for women in their 40s could be effective, but it is an individual decision. >> in the 40s, we find that the benefit is smaller, and that there are also harms. >> the harms include false-positives, which could be expensive financially and emotionally. the three groups don't agree when to start but do agree a women's risk increases gradually during her 40s. all of the different recommendations have 35-year-old susan fisher, mom to two boys, confused. >> i have a young family. and i want to make sure that i'm okay to be there for them. what age is the right >> dr. ji

new hampshire. we get more starting with nbc's andrea mitchell. andrea? lester. we have a dead heat in iowa and new an unexpected shake-up in the contest. >> reporter: to the surprise of everyone but bernie sanders, suddenly it is neck and neck. not just in sanders' neighboring state of new hampshire, but in iowa too. sanders and clinton tied within the margin of error in our new poll. even though clinton launched in iowa and blanketing the state since, trying to avoid a repeat of 2008 when she came in third. and clinton touts her strength against republicans in a new ad -- in our new poll, sanders outpaces her against republicans in hypothetical general election match-ups. in iowa and new hampshire. so after playing nice for months, now it is getting nasty. he recently criticized bill clinton's past behavior. >> what he did, i think, we could all acknowledge was totally, totally disgraceful and unacceptable. >> drawing strong criticism from her team. going there. he said he would run a positive campaign and he wouldn't go in for personal attacks. >> reporter: and

kristen welker, nbc news, charleston. in new hampshire. against ted cruz donald trump's done playing nice. >> he's a nasty guy. nobody likes him. nobody in congress likes him. nobody likes him anywhere once they get to know him. >> reporter: a new attack not on policy but personality. new york papers furious cruz hit trump's new york values. >> our friends in the media, seems like they lit their hair on fire. they were very confused. what are these new york values of which you speak? i would say in the rest of america people know exactly what that means. >> reporter: cruz arguing he's just using trump's own words from more than 15 years ago discussing aborgs and gay marriage. >> i lived in new york city and manhattan all my life. okay? so my views are a little bit different than if i lived in iowa perhaps. >> reporter: trump now fighting back against rivals who say he's too liberal. >> he's running for the conservative party's nomination. he should be a conservative. and he hasn't shown it. >> i'm conservative, but when it comes to differe

jacob rascon, nbc news, juarez, mexico. >>> we're back in a moment with why you might have to find a new place to shop after a major announcement from the retailer. >>> the world's largest retailer, walmart, is shutting down 269 stores. more than half in the u.s., and most are smaller walmart express stores. they are shifting focus to big super-centers and medium-sized neighborhood markets. about 10,000 employees will be affected in the u.s. >>> after months of negative headlines, chipotle is closing all of its locations at once next month. with a shutdown on during that time, chipotle will hold a national staff meeting about food safety. recent outbreaks of e-coli and the noro virus have damaged the brand and chipotle now faces a criminal investigation. >>> and dan haggerty has died. the actor was best known for his role as the star of the life and times of "grizzly adams" and the tv series that followed. he started out training animals for movies and working as a stunt man. that led to the acting role that would define his career as the bearded mountain man who becomes best friends

our nbc news investigation into the new complaints. >>> and recess time. we'll go to a school where the kids are getting a lot more breaks during the day, and the results may surprise you. "nightly news" begins now. >> announcer: this is nbc "nightly news" with kate snow. reporting tonight from charleston, south carolina. >>> good evening. from the gilyard center where they're putting the final touches on the big stage behind me for the big night in politics. the final democratic debate before the voting starts in iowa, just two weeks from tomorrow. our new nbc news/"wall street journal" poll sets the stage. it shows hillary clinton with a comfortable lead nationwide. 59% of democratic primary voters pick clinton. bernie sanders is at 34%. and martin o'malley trailing at just two. but in hypothetical head-to-head match skrupz with donald trump bernie sanders does better than hillary clinton. and with polls in iowa and new hampshire tightening over the past week there's a lot at stake here tonight. all while donald trump and ted cruz continue to battle it o

"nightly news" begins right now. >> announcer: from nbc news world headquarters in new york, this is "nbc nightly news" with lester holt. >> good evening. time is short, and the to-do list is long for the men and women running for president. in just six days, we will be counting actual votes in iowa. but in this final stretch, it's all about the polls and tonight they appear to confirm a dramatic reversal of fortunate among the two republican front-runners. donald trump now ahead in a state that once seemed to be ted cruz's to lose. and more worrisome for the cruz camp is trump is lining up what could be key endorsements. there's high drama in the democratic contest too. we've got both races covered. with katy tur. >> lester, never a dull moment in this race. donald trump now saying he will not be participating in thursday's fox news debate because he doesn't think megan kelly is fair. also touting two big including one from jerry falwell jr. the clock is ticking in iowa. six days left and donald trump is pulling ahead. today leading in five here. the race now a cage match between the

richard engel, nbc news, istanbal. >>> still ahead here 'tonigh s t, what to do. new guidelines fust out for breast cancer screening, different from other advice you've likely heard. what you should be asking your doctor. > also, they are paecking their trunks and headed for retirement. where ringling brsothers is wrapping and even though their dentures look clean, in reality they're not. if a denture were to be put under a microscope, we can see all the bacte a b that still exists on the denture, and that bacteria blmultiplies very rapidly. that's why dentists recommend cleaning with polijont everyday. po,ident's unique micro clean formula works in just 3 minutes, for a cleaner, fresher, brighter denture every day. [ music ] defiance is in our bones. citracal pearls. delicious berries and cream. soft, chewable, calcium plus vitamin d. everyone's lookin' red carpet ready. my man, lemme guess who you're wearing... toseen ail fungus!? whaaat?!? fight it! with jublia. jublia is a prescriptionanedicine... ...used to treat toenail fungus. use jublia as instructed your d