Nightly news begins right now. Announcer from nbc news World Headquarters in new york, this is nbc nightly news with lester holt. Good evening. A Surprising Development in the race for president leads our news tonight. A brandnew nbc wall street journal poll shows donald trump has slipped, falling behind ted cruz, among republican primary sloeters. Our poll has cruz now ahead at 28 , with trump at 26 . And marco rubio rounding out the top three at 17 . Trumps tumble from the top spot comes as he and cruz trade threats, dares and accusations ahead of saturdays South Carolina primary where trump still leads. Nbcs Hallie Jackson has late details. Reporter tonight a stunning shift in a republican race. A new national frontrunner, ted cruz. Its tremendously encouraging to be leading the field nationally. I think as a result did you ever think you would be here. That was always the plan. Thats how you win. You have to get to first place to win. Reporter its a 15point split from last month, trump slipping 7 points, cruz up 8. Republican voters have taken a pause decing whether or not they want to nominate donald trump to become president. Reporter cruz is burning it down in South Carolina with a scorched earth News Conference file a lawsuit. Reporter daring donald trump to sue him over this ad. Trump wants cruz to stop airing the spot, pointing to his current prolife stance. Trump supporters have shown a great likelihood of foregiving him for positions like that. Reporter cruz insists hell put the ad on tv more often now, even as trump doubled down on his threat in a town hall. Ive had Great Success in business, and Great Success with lawsuits. I dont know if well have a lawsuit, but we certainly want to keep someone honest. Reporter time will tell, teddy, trump calling him a liar. Their political bromance long dead. There are those who say you and your support of donald trump at that time has allowed him to be where he is today and to be in a position to talk about this stuff. Listen, hallie, there is a time and season for policy differentiation. Reporter but in South Carolina, its trump whos still dominating in the polls. Cruz trailing him, marco rubio close behind, and closing in. Late tonight picking up a new endorsement from South Carolinas popular governor. Rubio wasnt the only one looking for nikki haleys support. Jeb bush was, too. But our hypothetical headtohead matchup show that kasich would lose to trump. Only rubio and cruz would beat him. Im joined by chuck todd, our moderator of meet the press. Chuck, theres broad consensus if trump wins South Carolina, he would have this clear path to the nominati nomination. Do these National Poll numbers suggest things wont be that easy . I think what you see here with our new numbers is this, lester. Weve always told you, and weve been polling this for months, donald trump has a low ceiling, but a high floor, meaning hes never going to drop too low. But he always seems to struggle as the field strength to get over the 50 marker. As this field has sh rumpg, remember, this is the smallest field weve tested in the last six months. Weve seen that trump doesnt grow, everybody else does. This is a flashing yellow light for donald trump. Even if he wins South Carolina, hes going to have problems down the road as the field win nos. Much more from donald trump from a town hall event tonight. Things are rapidly changing in the democratic race, too, where Hillary Clintons once Comfortable Lead in nevada has all but evaporated, with Bernie Sanders ahead of saturdays vote. What looks like a long road ahead of them to the nomination, sanders and clinton are focused on securing the black vote. Kristen welker has more. Reporter secretary clinton is ramping up her outreach to black voters on the south side of chicago today. To make sure that no other young woman like sandra bland is ever pulled out of a car for no good reason and thrown into a jail where she is found dead. Reporter Sandra Blands mother by her said less than a year after her daughter was found dead in a texas jail. This as a new poll shows clinton and sanders now deadlocked in nevada. Her doubledigit lead in october evaporating to just a single point. Senator sanders, who is struggling to win over minorities, making his case at a rally in atlanta last night. But the headline came from rapper killer mike, quoting educator and activist jay elliott. Qualifies you to be the president of the united states. Reporter sparking a backlash on twitter. The accusations of sexism giving the Clinton Campaign an opening. Theres another way to make that point without necessarily offending people. What mike was trying to say in his way is people have got to vote for the candidate they think is the best candidate. Not based on gender. Reporter with the nevada caucuses just three days away as a woman, i dont need to vote for a woman just because im a woman. Reporter the race is up for grabs. If Bernie Sanders can win here, he will make the argument he can win anywhere, which is what Hillary Clinton doesnt want to hear. Reporter the stakes of every move couldnt be higher. Secretary clinton also had three fundraisers here last month. Senator sanders outpaced her in funding, mostly through online donations, another factor making the clinton team nervous. Kristen welker in chicago, thank you. The battle between apple and the fbi. The tech giant says its all about protecting your privacy, while the feds say its about national security. The iphone belonging to the San Bernardino killers which months after the attack is still locked. As our justice correspondent Pete Williams reports, apple is now being ordered to help the fbi break in. Reporter inside this black lexus, the fbi says it found a smartphone used by farouk that could contain critical evidence. Did they plan more attacks, was anyone else involved . It must be unlocked with a combination. But trying to get wont work because after ten unsuccessful tries, the contents of the phone are permanently scrambled, lost forever. Now a judges order apple to create and install software on that phone to defeat the security, allowing an fbi computer to keep entering numbers until it reaches the right combination. Privacy advocates said they will help fight the order. If you build a back door, or master key into a lock, you cant control that only good guys are going to use it and bad guys are not going to be able to use it. Reporter after months of saying that it cannot get into a locked phone, apple now says it should not be forced to do so. In a letter to customers, ceo tim cook says, if apple creates the software, and it fell into the wrong hands, it could unlock any iphone. A blow to customers who rely on Companies Like apple to protect their data. They do business all over the world. And if they give this kind of access to the u. S. Government, they may have to give it to the russians, they may have to give it to the chinese, and apple simply doesnt want to do this. Reporter it comes against the back drop of an act of terrorism. The husband of one of those killed in the shootings said apple is wrong. Ill say it to apple, peoples lives matter. Reporter new york citys Police Commissioner agrees. The right to privacy is not a total life in the sense that it is being used for criminal about purposes. Reporter before the San Bernardino shootings, the majority in an nbc news poll said they were worried the government would go too far in terrorism investigations and violate the privacy of citizens. After the attack, the majority worried the government would not go far enough. Apple said it will fight this new order in court. Pete, thank you. Overseas, dozens are dead and injured after a bomb exploded near turkeys parliament. A horrific attack in the heart of a strategic u. S. Ally. The question tonight, who did it . Nbcs kelly cobia reports. Reporter a fireball in the heart of turkeys capital at the height of rush hour. Flames shot several feet into the air as people scrambled to safety. Police and the military sealed off the area, while emergency workers rushed in to help the injured. The target was the turkish military. The powerful car bomb exploding just as buses carrying officers and soldiers drove by the armed forces headquarters, stopping at traffic lights. More than two dozen are dead, some 60 injured. The countrys deputy Prime Minister called it a wellplanned act of terrorism. The latest in a string of attacks in places many considered safe. Ten German Tourists killed in a suicide bombing in istanbul. More than 100 killed at a peace rally in ankara. Isis blamed for both attacks. Turkey is fighting the terror group in syria and iraq, but its also at war with kurdish militias. Its in the eye of the storm. It faces a strategic predicament. It faces multiple insurgent sis. Reporter turkeys president is determined to fight those who carried out the deadly bombings. Pope francis is wrapping up his trip to mexico with a historic crossborder mass. The event, a few hundred feet from the u. S. Border, attracting tens of thousands of followers on both sides. As nbcs Anne Thompson explains, the pope is making an emotional plea of the controversial issue of immigration. Reporter a simple gesture, a powerful message, at the u. S. Border fence, pope francis builds a symbolic bridge from mexico on immigration. Francis the son of immigrants, seeking to put a human face on the people fleeing what he called grave injustices, poverty, exploitation and violence. Among the hundreds of thousands here to see him, 21yearold Jasmine Flores crosses the border every day to go to school. For him just to come here to juarez, to come to the border, it means everything to us. Reporter no longer the murder capital of the world, juarez is still a dangerous place. This father runs a shelter for immigrants. He says he hopes francis can make americans see the people he helps every day should be treated with dignity. As he does on nearly every foreign trip, francis visited a prison. One of the inmate musicians overwhelmed. This evenings mass broadcast on both sides of the border. Religion reaches over walls, over mountains. Reporter the joy on the popes face this trip marred only by a brief flash of anger when an overzealous fan nearly pulled him down onto a person in a wheelchair. Dont be selfish, he said. The vatican says mass here on the border is not a political statement. But a moral one. By a pastor trying to unite a divided world. Lester . Anne thompson in mexico, thanks. This could affect millions of men who suffer from low testosterone. Low t has been linked to loss of energy, muscle mass and sexual function, to increase vulnerability to illness. Now as tom costello tells us, new research by the National Institutes of health, shows testosterone replacement therapy may have some benefits. Reporter its a nearly 5 billion a year market. Millions of men 40 and over are on testosterone replacement therapy, hoping to boost their energy, boost their mood, sexual desire and function. This 62yearold said at the age of 55, he suddenly began to feel tired and depressed. I just felt off. And at the gym, i started losing ground. Reporter diagnosed with low t, he began testosterone replacement therapy. My body mass came back to where it was, my energy was better, libido was a little better. Reporter now, for the first time, a National Study has found that a testosterone repla replacement gel provided some benefits to men 65 and older who suffered from low t. Testosterone treatment improved their sexual function, their mood, and reduced depressive symptoms. And perhaps also improved walking. Reporter but researchers insist its too early to say whether all men with low t should be on replacement therapy. Previous studies have found that boosting des toss troen might lead to an increased risk of heart attack and prostate cancer. Millions of men say testosterone has restored their quality of life. In texas, 68yearold dr. Bill reilly said testosterone therapy changed his life. There were some risks of taking testosterone. But the benefit far outweighed any risk. Reporter hes such a believer, hes now the medical director for a chain of lowt clinics. As the baby boomer generation looks to offset the effects of aging. Tom costello, nbc news, washington. Still ahead tonight, know what youre eating. The package may say Parmesan Cheese, but you may be surprised to find out what else may actually be in it. Some of it may not even be cheese. Another piece of the mystery solved over who will split the biggest Powerball Jackpot in history. Many of us say a plate of pasta wouldnt be the same without some Parmesan Cheese. A filler can be derived from wood pulp. How do you know what youre really buying and eating . Nbcs Olivia Stearns has more. Reporter its no secret that americans love their cheese. Just ask seinfelds george costanza. Just bite into it like its an apple. Reporter an fda investigation raising the question, whats in the cheese youre eating. In 2013, the agency targeted castle cheese, saying what the company labeled as 100 Parmesan Cheese was actually a blend of cheaper cheeses and sell you lohse, an organic filler that can be derived from wood pulp. Blasting the company in a letter, quote, your Parmesan Cheese products do not contain any Parmesan Cheese. The company took corrective action but ended up filing for bankruptcy and could not be reached for comment. The fda allows up to 4 filler products like cellulose and cheese. But experts say its whats in the other 96 that might not be exactly what you think. Experts say some companies go too far. Theyre trying to do things that we dont notice. But to cut corners so they can make money. Reporter the food brought cases of mislabeling, citing some involving certain brands of cheese, extravirgin olive oil and seafood. Top chefs like tom say most people dont have the palate to tell the difference. This is a problem of labeling. What were being sold, or marketed as something as fresh, or local, and it really isnt at all. Reporter a possible contributing factor, dr. David kessler said the fda focuses on ensuring food safety. Not investigating truth in advertising. We cant forget that there are people, there are companies who cheat the system. Reporter that may be great news to fans of real Parmesan Cheese. Olivia stearns, nbc news, new york. Were back in a moment with a new leader of the pack from this years west minister dog show. The white house has announced that president obama will not attend a funeral for Supreme CourtJustice Antonin Scalia on saturday. Instead, the president will pay his respects on friday when the late justice lies in repose in the courts great hall. Vice president joe biden, however, is scheduled to attend scalias funeral. George gains has died. Some of his memorable roles, he was punky brewsters dad in the 80s tv show. And in seven Police Academy movies. Many remember him with the season opera star with a crush on tootsie. George gaynes was 98 years old. The best in show at the Westminster Dog Show pointer named c. J. A 3yearold who beat out nearly 3,000 competitors. Today the top dog celebrated at the top of the empire state building. When we come back, theyve been keeping the secret for weeks, but now meet americas newest instant multimillionaires. Wind taking its toll. Vo gts snaprees acrosshe bay area. Live cam 161 drivers maneuver rain slicked roads. Wx wall and, right now. Ng the heiest rain how much rainfall to expect overnight. Next close the news is next. Janel finally tonight, a florida couples life just changed forever. Theyve cashed in the second of three Winning Tickets for last months 1. 6 billion Powerball Jackpot. As our Janet Shamlian tells us, it was tough for them to keep their excitement under wraps. Reporter Maureen Smith and david have known they were powerball winners for weeks. But its a secret they kept even from their own family. Lost a lot of sleep. I lost over ten pounds. A lot of pacing at night, let me tell you. Reporter the winning numbers are what she said she played for years. They bought only two tickets. Just the one. 3 investment. Reporter david is an engineer who plans to retire. But since the drawing has still been going to work. The first day i arrived late at work, they all suspected i won. Reporter david and maureen are splitting the record 1. 6 billion jackpot with two other winners. One in california who hasnt come forward, and john and Lisa Robinson from tennessee. Who appeared on today, just two days after the drawing. Unlike the robinsons, david and maureen took time to claim their prize. Still, they were anxious about this day. Sweating it. Reporter the couple told lottery officials when they arrived here today they would be taking the lump sum option, thats 327 million, plus change, before taxes. Melbourne beach, florida, the Mystery Beach is finally over. We had no idea. They acted normal. Reporter the couple say theyll take care of family, donate to charity and david may buy a car. Otherwise, no big splurges planned. I want to get a massage. Reporter Janet Shamlian, nbc news, tallahassee, florida. That will do it for us on a wednesday night. Im lester holt. For all of us at nbc news, thank you for rain returns to the bay area. Heres a live lookut nbc bay area news starts now. Right now at 6 00, rain returns to the bay area. A live look outside our Traffic Cameras capturing the rain coming down right now in parts of the bay area. Thanks for joining us. Im janelle wang. Im jessicaing a gi aguirre. The rain is finally back. You can see the green on our satellite radar welcome back after weeks of dry weather coverage. We begin with chief meteorologist jeff rainieri. Weve been talking about this storm and its here yes. And really great to finally start to get these rain drops here across the bair bay area. You can see the center of low pressure offshore. But its the cold front that will provide some of the heaviest rainfall over the next 3 to 6hour period. Right now its really beginning to pick up on a clip. This is the most active its been all day when it comes to rainfall. You can see throughout the north bay not only some moderate pockets, a little bit of yellow and orange popping up showing heavier pockets from ravell to san rafael from the Richmond Bridge towards emeryville and terk lease and vallejo. You can seat rainfall beginning from oakland to orinda, lafayette, walnut creek, san ramon and beginning to see showers developing in dublin, pleasant ton and livermorliverm. Bad commute from the San Francisco airport all the way down towards palo alto. Fina