FORT WAYNE, Ind. — In his final pitch to voters, President Donald Trump implored Republicans on Monday to help preserve "fragile" GOP victories that could be erased by Democrats as he closes out a midterm campaign that has been defined by his racially charged rhetoric, hard-line immigration moves and scattershot policy proposals.

Trump's shadow has hung over the midterm elections that will determine the future of his presidency, with the monthslong fight serving as a testing ground for his nationalist appeals and the strength of the coalition that powered him to the White House two years ago. Acknowledging the stakes in the closing days of campaigning, Trump stressed to voters that everything is on the line when they go to the polls.

"It's all fragile. Everything I told you about, it can be undone and changed by the Democrats if they get in," Trump told supporters on a telephone "town hall" organized by his re-election campaign. "You see how they've behaved. You see what's happening with them. They've really become radicalized." Trump spent his final hours on the trail Monday in Ohio and Indiana, with a further stop planned in Missouri. One day before polls closed, he harshened his rhetoric on illegal immigration and lobbed attacks at Democrats.

In a Monday tweet, he warned that law enforcement was "strongly notified to watch closely for any ILLEGAL VOTING which may take place in Tuesday's Election (or Early Voting)." Trump has falsely claimed that millions of illegal votes were cast in 2016, depriving him of a victory in the popular vote, and he has stoked concerns, without providing evidence, of rampant fraudulent voting.

As he lambasted his rivals on the campaign trail, Trump struck a gentler note in an interview Monday with local media conglomerate Sinclair Broadcasting, saying he regretted some of his rhetoric.

"I would like to have a much softer tone. I feel to a certain extent I have no choice, but maybe I do," Trump said.

He has also sought to distance himself from any potential blame if Republicans lose control of the House, saying, "My primary focus has been on the Senate." Whatever the outcome, Trump made clear he knew his political future was on the line.

"In a sense, I am on the ticket," he told a raucous crowd in Cleveland.

He warned earlier on the telephone town hall to get out and vote because "the press is very much considering it a referendum on me and us as a movement." Republicans are increasingly confident they will retain control of the Senate, but they face Democratic headwinds in the House. In an interview with The Associated Press last month, Trump said he would not accept blame for a GOP defeat at the polls.

Trump has maintained a busy campaign schedule in the final stretch of the race, with 11 rallies over six days. In the closing days Trump has brought out special guests to join him on the campaign trail. Country singer Lee Greenwood performed Trump favorite "God Bless the U.S.A." in Chattanooga, Tennessee, and was expected to appear Monday with the president in Cape Girardeau, Missouri. Fox News personality Sean Hannity and conservative radio host Rush Limbaugh were also slated to be "special guests" at the final rally, according to Trump's campaign, though Hannity insisted on Twitter he would only be "covering (the) final rally for my show." At his rallies and on Twitter, Trump's closing argument has largely focused on fear — warning, without evidence, that a Democratic takeover would throw the country into chaos, spurring an influx of illegal immigration and a wave of crime.

With the election approaching, Trump seized on the caravans of Central American migrants to reinforce an immigration message that recalls the racially charged immigration talk of his 2016 campaign. Faced with low Republican enthusiasm, Trump calculated that immigration would again be an animating issue for his base. He also used the confirmation battle for Supreme Court Justice Brett Kavanaugh to stir up his most loyal supporters.

At his rallies, Trump frequently declares that 2018 is the election of "Kavanaugh and the caravan." He has pushed forward with the rallies amid news events that would have halted previous leaders — holding a massive rally the same day a gunman massacred 11 people in a Pittsburgh synagogue.

Trump's rallies typically follow their own sort of script.

The same soundtrack — heavy on Elton John and The Rolling Stones with a little Backstreet Boys and Rihanna thrown in — plays at the same earsplitting decibels. The same red "Make America Great Again" hats dot the crowd, which happily chants along with the greatest hits of the 2016 campaign, including "Lock Her Up," ''Build the Wall" and a derogatory message toward a certain cable news network. Night after night, Trump unleashes grievances against the media, attacks his political foes, showcases his own accomplishments and promises that he alone can achieve the nation's potential.

Though the candidates he has traveled to support often feel like supporting actors in the theater of a Trump rally, the president has more urgently outlined the need for the Republicans to hang onto power. And he has sharpened his attacks on Democrats while playing up doomsday scenarios if they were to gain power.

In recent stops, Trump has directly targeted favorite foes House Minority Leader Nancy Pelosi and U.S. Rep. Maxine Waters and argued that Democrats would plunge the country into Venezuela-like chaos.

Trump's midterm efforts will not stop with his Missouri rally on Monday night. He plans to spend Election Day encouraging voters to get to the polls from the White House.

AP