By Nathan Layne, Gabriella Borter and Tim Reid
INDIANOLA, Iowa (Reuters) -Republican presidential candidates exhorted their supporters to brave glacial, life-threatening temperatures in Iowa to vote in the party's first nominating contest on Monday, amid fears a predicted record cold snap could keep many voters at home.
The icy weather in the Midwestern state has become a wild card in the crucial contest that could help seal former President Donald Trump's bid to become the Republican nominee to face Democratic President Joe Biden in November's general election.
His top rivals, former U.N. ambassador Nikki Haley and Florida Governor Ron DeSantis, are banking on good showings in Iowa to puncture Trump's air of inevitability. But the extreme cold could scramble those calculations by suppressing voter turnout.
At a rally in Indianola, Trump urged his supporters to dress warmly and joked that single attendees might meet their future spouses if they show up on Monday night.
"You can't sit home ... Even if you vote and then pass away, it's worth it," Trump said to laughter. More than 500 supporters wearing trademark red baseball hats as well as heavy coats, earmuffs and boots had packed into the venue.
The highly regarded Des Moines Register/NBC News poll released late on Saturday found that Trump had the most supporters saying they were very enthusiastic about his candidacy, suggesting they may not be deterred by the forecast for the coldest Iowa caucus night ever - minus 20 degrees Fahrenheit (minus 30 degrees Celsius).
Iowa highways are lined with abandoned cars stuck into snowbanks, political yard signs have disappeared under snow, and one reporter said on social media that her coffee had frozen.
The poll showed Trump with 48% of support, while DeSantis, who has staked his bid on a strong showing in Iowa, had slipped to third place with 16%. Haley, who has capitalized on donors' disappointment with DeSantis' lackluster campaign, had jumped to second place with 20%.
Haley posted a video of herself speaking outside next to a mound of snow as the wind blew through her hair. "I know it's cold, but we need you out there," Haley said. "Let's finish this strong."
Jane Van Voorhis, a 61-year-old university fundraiser in Iowa City, said she planned to switch her voter registration from Democrat to Republican "fleetingly" on Monday to cast an anti-Trump vote for Haley. Iowa allows voters to change their party affiliation on the day the caucuses are held.
DeSantis also urged his supporters to brave the cold, saying their votes would have greater weight if the weather leads to significantly lower turnout.
"We're telling our supporters: You go out, you bring some friends and family. That is going to pack a big punch," he told CNN's "State of the Union".
The 2016 Republican caucus saw record turnout, with about 187,000 votes cast, or approximately 29% of the state's registered Republican voters at the time. Republican turnout was closer to 18% in 2012.
Iowa Republican Party Chair Jeff Kaufmann said he was expecting strong turnout as long as there isn't snowfall and icy road conditions that hinder travel.
"The temperatures are the least of my concerns in terms of depressing turnout," Kaufmann said at a press roundtable hosted by Bloomberg News in Des Moines on Sunday. "Iowans know how to dress for that."
With only the margin of Trump's victory in Iowa appearing to be the big unknown, DeSantis and Haley are fighting furiously for second place, hoping for momentum to carry them to New Hampshire. Entrepreneur Vivek Ramaswamy is also in the running, but his campaign has been flagging for several months.
Trump's popularity with the Republican base shows his supporters' willingness to look past the scores of criminal charges he is facing, as well as his role in the Jan. 6, 2021, attack by his supporters on the U.S. Capitol.
He has also faced little blowback from supporters for increasingly authoritarian language that has echoes of Nazi rhetoric, including comments that undocumented immigrants were "poisoning the blood of our country."
On Sunday, Trump was endorsed by North Dakota governor and former 2024 presidential candidate, Doug Burgum, as well as Florida Senator Marco Rubio, whom Trump defeated for the 2016 Republican presidential nomination.
From 7 p.m. CST on Monday (0100 GMT on Tuesday), Iowans will gather in school gymnasiums, bars and other locations to debate the Republican candidates before casting secret ballots. Results are typically announced within a few hours.