Nightly news begins right now. This is nbc nightly news with lester holt. Good evening, there are exactly three weeks to go until election day. And with donald trump continuing today to sew seeds of doubt about the integrity of the voting system, president obama jumped into the middle of things, advising trump to stop whining. Trumps conspiracy theories and mantra define much of the home stretch of the campaign, along Hillary Clintons daily email embarrassments. If theres a shakeup in the state of this bitter race coming, it could come tomorrow night when the two meet in las vegas for their final debate. Thats where Hallie Jackson leads us off tonight. Hallie . Reporter hi, lester. Donald trumps aides say he spent part of his morning preparing for the final faceoff. As we learned late tonight, hes expected as one of his guests here to vegas tomorrow, a signal everything is now on the table. Donald trump tonight complaining of corruption voter fraud is all too common. Reporter to president obama, hes just complaining. Id advise mr. Trump to stop whining and go try to make his case to get votes. Reporter the president slamming trump for his rhetoric about a rigged system. I have never seen in my lifetime or in modern political history any trying to discredit the elections. Reporter even some republicans like marco rubio agree trump should stop stoking voter fraud fear in the face of overwhelming evidence our elections arent rigged. They even want to try and rig the election at the polling booths where so many cities are corrupt, and you see that. Reporter trump, defiant and undaunted, three weeks. Trailing Hillary Clinton, hes now trying to shake up the race by showing he can shake up washington. Proposing term limits for members of congress. Hes running against the establishment, but still chased by his own controversies, like an accusation of Sexual Misconduct against him from a former People Magazine writer. Not verified by nbc news, and denied by trump, the magazine today publishing the accounts of five people who say the writer told them what she was with the writer when they encountered Melania Trump later in new york. It was not true. So how we could believe her . That never happened. To turn the tide, trump needs to rally his base to make sure they show up in three weeks. Every time theres been open running room for donald trump, he doesnt advance the ball. Tomorrow nights his last chance. Reporter in the audience as his guest tomorrow, the mother of shaun smith, who for her sons death in the benghazi attack. For trump, a focus on clintons controversies instead of his own. Hallie jackson, nbc news, las vegas. Reporter im andrea mitchell. Tonight Hillary Clinton arriving in las vegas, site of tomorrows final debate showdown, as the clinton team prepares for the home stretch. The strategy, in the debate, stick to issues, try to appear president ial, no matter what donald trump does. With trump trying to rattle clinton by bringing the mother of an american killed in benghazi to the debate. Benghazi is something that there have been seven to it is a resolved matter. Its not resolved for the people who died, jen. We think its a resolved issue in the voters minds. Reporter also dealing with the torrent of stolen emails released by wikileaks. Tonight, new messages, one from Campaign Chairman john podesta calling Bernie Sanders a dufus for criticizing an International Climate change deal. Another, three months before clinton nailed the nomination, podesta listing potential running mates in what he calls them by race and gender. On the list, apples tim cook, bill and melinda gates, sanders down at the bottom of the email in a category all by himself. Despite those emails, tonight team clinton sending sanders to arizona, going for a win in red states. Michelle obama going there thursday. Mr. Trump is the least qualified, the least qualified candidate in the history of this country. Clinton getting more backup tonight, after an fbi agent said he felt pressured by the state department not to label one of clintons emails classified, a charge denied by both the fbi and the state department. President obama weighing in. I think youve heard directly from both the fbi and the state department that the accounts that have been put out there are just not true. Reporter clinton aides tonight just laughing off Donald Trumps recent charge that she is doping for tomorrow nights debate, nonstop travel to the battleground states, ohio, pennsylvania, north carolina, new hampshire, and florida, all in the next week. Lester . Andrea mitchell tonight, thanks. And for more now on where the election stands and what we should be looking for heading into tomorrows final debate, im joined by our political director and moderator of meet the press, chuck todd. Chuck, when you look at the polls over these many months, the margins have changed here t changed that much. Were into the final three weeks, the big debate tomorrow, what could happen that might change things . To me, thats the most important question. Here weve had ten straight months of polling and campaigning by these two, and the negative feelings at the start of this year that the public had for both of them are still there. They feel more negative about him than her. So the question is, is there anything in the next three weeks . Obviously, if youre trump, you need to make this debate work i think the only thing that can change trajectory in this race is some unknown incident, some unknown issue that pops up. Because at this point, i think everything feels like its starting to settle set into concrete here. The only time weve seen anything move at all is when we heard the words of donald trump in that videotape. Thats the type of issue that would have to pop up to actually change the direction of this campaign at this point. Who has more riding on tomorrow . Oh, its donald trump by a mile. He has debate, almost a knockout performance in order to change the direction of this race. All right, chuck todd, thank you very much. Well have full coverage and analysis of tomorrows final president ial debate in las vegas, starting at 9 00 eastern, 6 00 pacific right here on nbc. Turning now to iraq and the americansupported campaign to take back the city of mosul from isis. President obama said today what troops on the front lines have already discovered, so far commanders say the operation is going according to plan, but are warning about what isis may do overseas in retaliation. Our chief Foreign CorrespondentRichard Engel is in the region and spoke exclusively with the general leading the american effort. Reporter hows it going . Its going well. Reporter in his first interview since the offensive to push isis out of mosul began, Major General gary volesky said his troops are providing air support and heavy artillery, but not the iraqis have the momentum, they know it, and they want to get there as quickly as they can. Reporter we followed iraqi troops to the front line, south of mosul to see for ourselves. We made our way to the newly liberated village of huud. Shes happy, said a man, pushing his 80yearold grandmother, shes happy to see the soldiers. But why were these people carrying white flags and leaving on, even though villagers say theres still isis fighters here. And what we saw next was a war planners worst nightmare, entering this sunni village were shiite militias. In a country thats seen civil war between these two sects of islam, its a dangerous mix. But what happens here could have International Consequences as well. General volesky is retaliation for losing mosul, isis could launch terror attacks on targets in the west. Thats what were worried about from my perspective, back at home is, when mosul falls, how are they going to try to deflect the attention . Reporter but for now the troops are focused on the task at hand. Mosul is where the socalled Islamic State or caliphate was born. And its here that the general believes it will die. Theres not going to be a caliphate. Not in iraq, clearly. Reporter this battle is just beginning, and these are just the first of what aid agencies warn would be more than a Million People driven from their homes. They suffered under isis, now theyre paying the price for yet another fight for mosul. While u. S. Backed iraqi troops are advancing toward mosul, isis is saying that nothing is wrong. Its propaganda today putting out images of people at work, eating kebab in the city, life as normal. Lester . Richard engel, thank you. Back home, much of the eastern half of the country remains in the middle of a fall heat wave this evening. While new york was one degree short of a record new high for this date, highs for this date were set throughout the northeast and down to texas, with temperatures in the mid to upper 80s. More of the same is predicted for tomorrow when dozens of records Indian Summer in full swing. Now to the brutal and shocking execution caught on camera in mexico. A federal judge who reportedly played a role in drug king pin Joaquin El Chapo guzmans extradition process to the u. S. Was shot in the back of the head while taking a jog. The broad daylight execution is sending shock waves through that country. We get the latest from nbcs miguel almaguer. Reporter the shocking Surveillance Video shows the judge jogging when a gunman runs up from behind, a point blank execution of Vicente Bermudez zacarias, a 37yearold mexican judge was reportedly involved in the extradition process of drug king pin Joaquin El Chapo guzman, and other high profile cartel members. Addressing the nation, mexicos president promised a full investigation. El chapo is behind bars in federal prison, but experts say he still has connections to order brutal hits. Last month, mexicos army says el chapos soldiers dead. El chapos lawyer says the widely feared drug lord who escaped from prison twice using tunnels like this one, was not involved in the murder. The judge also presided over other cartel cases and had not requested personal security. Mexican Drug Trafficking organizations have a strategy to corrupt high level government officials, take my silver or take my lead, and its been reporter with el chapo facing extradition to the u. S. Next year, the investigation into this brutal hit is just beginning. A crime designed to send fear through a nation doing exactly that tonight. Miguel almaguer, nbc news. There is news tonight for millions who depend on Social Security. Dont expect a big raise coming next year. Retirees will get a. 3 increase in adds up to about 4 a month for the average recipient. The average monthly Social Security payment now 1,238. The cost of living adjustment will be small because inflation is low and thats due in part to low gasoline prices. Still ahead tonight, a warning for parents, an alarming rise in overdoses and deaths from a new drug more powerful than heroin being purchased by teenagers legally online. Also, he has a way with words, this is why the nobel comm the literature prize. But so far he hasnt across the country, paramedics are seeing a rise in Overdose Deaths from powerful drugs legally bought online and shipped to teenagers in the mail. The drugs are synthetic opioids, stronger than heroin, and chemically designed to get around laws in the united states. One of those drugs is under siege. Lets get more on the story now from gadi schwartz. Reporter in park city, utah, pain and disbelief. I feel lucky that our last words were i love you. Reporter they were only 13, two best friends in middle school dead, reasons still under investigation. But Police Suspect a new drug more than twice as powerful as heroin that you can legally buy online. Our students that have been involved, we friends house. Reporter in park city schools, students were calling it pink and secretly talking about it over snapchat. We looked at computers, social media, and started to see a trend. The term pink kept popping up. Reporter now worried parents are warning their children about the drug, a synthetic opioid. Look, theres pages and pages of places you can buy this. Reporter melissa davidsons daughter jane said pink and the deaths of the two boys are all her classmates can talk about. Unregulated chemical compounds being shipped to the u. S. From abroad. So far, eight killed in florida this year, over 50 deaths nationwide, while only four states have made it illegal. The dea now pushing for new laws to ban the chemical compound, while the most effective protection may start with conversations between parents and their children before its too late. You know, i just worry about you. I cant imagine the kids im in math class not being there one day. One bad decision can have permanent, lifealtering consequences. Yeah. Reporter for now, this mother hopes her love can overcome a drugs deadly pull. Gadi schwartz, nbc news, park city, utah. And up next here tonight, this years nominees to the rock when it was announced last week that American Music legend bob dylan had won the nobel prize in literature, the news spread around the world and just about everyone had something to say about it. But dylan himself, a man of memorable words, has chosen to remain silent. We get the story from nbcs keir simmons. . . Reporter awarded the worlds highest literary honor, tonight its unclear whether bob dylan is the voice of a generation saying nothing about the accolade. I think him not responding to the Nobel Committee, its really in the spirit of his creative life. Ive never been that kind of performer that wants to be one of them, one of the crowd. Reporter after the Nobel Committee received no more than a friendly acknowledgement from a dylan collaborator, Officials Say theyve given up trying to track him down. Hes not hard to find, on a u. S. Tour tonight in new mexico. Reporter back in 2001, he did accept a golden globe for best original song. His speech was 16 seconds. This is quite something really. Thanks, curtis. Thanks, Hollywood Foreign press and thank my band, the Record Company and everybody in my family, and thats about it, really. Reporter tonight, those who questioned honoring a musician with a nobel say if hes not going to show up, he shouldnt get it. But his fans just see and he does it for him. . The times they are a changing . . Reporter keir simmons, nbc news, london. And while none of them are lucky enough to be nobel prize winners, a new group of big musical names will soon be in exclusive company. The nominees for this years rock and roll hall of fame class includes pearl jam, janet jackson, journey, tupac, chaka chan and joan baez. Others acts up for addiction, the cars, and more. The inductees will be announced in december. When we come back, inspiring america. Well show you what happened when a college turned its losing Football Team into a winning farm finally tonight, a Small College in texas got rid of its losing Football Program but in its place, the kids the big leagues. Steve pattersons has tonights inspiring america report. Reporter its said in texas, the state religion is football. But at Paul Quinn College in dallas, the team was so bad they didnt have a prayer. We couldnt afford football. Reporter so when the school brought in a new president , he shocked the lone star state, by getting rid of the game, and replacing it with a farm. Turns out it wasnt very popular with the football players. Ive got basil, swiss chard helps students grow while learning to tend a crop, all in exchange for cash and college credit. Its about teaching them accountability, about how to show up on time, ready to work. For the actual pea reporter the yield, 30,000 pounds of organic produce. Enough to feed the neighbors in one of the worst food deserts in dallas. Theres no access to Fresh Produce within a mile radius. We serve as that hub for Fresh Produce for our neighborhood. Reporter once nonprofits and sold to local restaurants. But by far, the biggest client is the home of the dallas cowboys, ending up in kitchens right here at at t stadium. When did you guys pick this . We picked these yesterday afternoon. Very nice. Thats really, really cool. Reporter today the school that kicked football out is feeding football fans. We believe in it. This is something that was effortless and it makes a lot of sense, and it transcends into what we do with our reporter this fall, the farm is flourishing and enrollment is up. To know that if you work hard, if you apply yourself, you can make a way out of no way. Reporter a winning season on the field, tilling instead of touchdowns. Steve patterson, nbc news, dallas. Thats gonna do it for us on a tuesday night. Im lester holt. For all of us at nbc news, thank you for right now on news 3 live at 6 00 24 hours from now the final president ial debate will be starting in las vegas. Both candidates are in town. Were tracking how they are prepping. Layoff cans at the ufc. Why and how many local employees could be affected. New developments just in on this brutal fight between students of two the candidates both came into town plenty early to get ready. Hillary clinton, the first to get here this afternoon. Then a short time ago, donald trump touching down. Their confrontation at the Thomas Mack Center happens tomorrow evening. Good evening. Im jim snyder. Im reed cowan. You know, unlv is getting ready for its campaign closeup. Thousands of journalists are between clinton and trump. It will be their last chance to speak to millions of americans at once. We have Team Coverage of our top story tonight. We start with jeff gillan and the final preparations. Jeff . Reporter thats right, reed. Good evening from campus. Tomorrow night could be a record audience and they are not only watching here. They are watching abroad, too. Me of all people getting tailed for the day by danis its not every day im on danish tv. Ive never been on danish tv t so i asked how interested europe is in this election. Huge, he says. Its fascinating, but its also very much like a reality show. Its sort of it seems like american politics have hit a no low. Reporter not hard to see why. Trump talking like a teen, the