INDIANOLA, Iowa – Republican presidential candidates exhorted their supporters to brave glacial, life-threatening temperatures in Iowa to vote in the party’s first nominating contest on Jan 15, amid fears that 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 United Nations 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 keeping people indoors and suppressing voter turnout.

At a rally in Indianola, Trump urged his supporters to dress warmly and joked that single attendees might meet their future spouse if they show up on Jan 15 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 the venue.

The highly regarded Des Moines Register/NBC News poll released late on Jan 13 found that Mr Trump had the most supporters saying they were very enthusiastic about his candidacy, suggesting that they may not be deterred by the forecast for the coldest Iowa caucus night ever – minus 30 deg C.

Iowa highways are lined with abandoned cars stuck into snow banks, political yard signs have disappeared under snow, and at least one reporter said on social media that her coffee had frozen.

The poll showed Trump with 48 per cent of support in the conservative and religious state, while Mr DeSantis, who has staked his bid on a strong showing in Iowa, had slipped to third place, with 16 per cent of support.

Ms Haley, who has capitalised on donors’ disappointment with Mr DeSantis’ lacklustre campaign, had jumped to second place with 20 per cent.

She 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,” she said. “Let’s finish this strong.”

Ms Jane Van Voorhis, a 61-year-old university fund-raiser in Iowa City, said she planned to switch her voter registration from Democrat to Republican “fleetingly” on Jan 15 to cast an anti-Trump vote for Ms Haley. Iowa allows voters to change their party affiliation on the day the caucuses are held.

Mr 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.

Typically the Republican nominee is not determined until later in the year after many states have held their contests. But Mr Trump is so far ahead of his rivals that it will be hard to stop him if he wins in Iowa and the second contest in New Hampshire on Jan 23.

The 2016 Republican caucus saw record turnout, with about 187,000 votes cast, or approximately 29 per cent of the state’s registered Republican voters at the time. Republican turnout was closer to 18 per cent in 2012.

Iowa Republican Party chair Jeff Kaufmann said he was expecting a strong turnout as long as there are no icy road conditions and snowfall that hinder travel.

“The temperatures are the least of my concerns in terms of depressing turnout,” Mr Kaufmann said at a press roundtable hosted by Bloomberg News in Des Moines on Jan 14. “Iowans know how to dress for that.”

With only the margin of Trump’s victory in Iowa appearing to be the big unknown, Mr DeSantis and Ms 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 so far to look past the scores of criminal charges Trump is facing, as well as his role in the Jan 6, 2021, attack by his supporters on the US 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 Jan 14, 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 7pm local time on Jan 15, Iowans will gather for two hours in school gymnasiums, bars and other locations to debate the Republican candidates before ranking them in order of preference. Results are typically announced within a few hours. REUTERS