Voting begins on Monday in icy Iowa as former US president Donald Trump eyes a victory that would send a resounding message that neither life-threatening cold nor life-changing legal trouble can slow his march towards the Republican Party’s 2024 nomination.

The Iowa caucuses are the opening contest in the months-long Republican presidential primary process.

Caucus participants will gather inside more than 750 schools, churches and community centres to debate their options, in some cases for hours, before casting secret ballots.

While Mr Trump projects confidence, his one-time chief rival, Florida governor Ron DeSantis, is fighting for his political survival in a make-or-break race for second place.

Former UN ambassador Nikki Haley, the only woman in the race, stands in DeSantis’ way.

They have competed aggressively in recent weeks to emerge as the clear alternative to the former president, who has alienated many Americans and could end up being a convicted felon by the year’s end.

“I absolutely love a lot of the things (Trump) did, but his personality is just kind of getting in his way,” said Hans Rudin, 49, a community college adviser from Council Bluffs, Iowa.

He said he supported Mr Trump in the past two elections, but will support Mr DeSantis on Monday.

Polls suggest Mr Trump enters the day with a massive lead in Iowa as Ms Haley and Mr DeSantis duel for a distant second.

Entrepreneur Vivek Ramaswamy and former Arkansas governor Asa Hutchinson are also on the ballot, as is former New Jersey governor Chris Christie, who suspended his campaign last week.

With the coldest temperatures in caucus history expected and dangerous traveling conditions in virtually every corner of the rural state, the campaigns are bracing for a low-turnout contest that will test the strength of their support and their organisational muscle.

The final result will serve as a powerful signal for the rest of the nomination fight to determine who will face Democratic President Joe Biden in the November general election.

After Iowa, the Republican primary shifts to New Hampshire, Nevada and South Carolina over the coming weeks before moving into the rest of the country this spring.

The ultimate nominee will not be confirmed until the party’s national convention in July, but with big wins in the opening contests, Mr Trump will be difficult to stop.

Mr Trump’s political strength heading into the Iowa caucuses, which come 426 days after he launched his 2024 campaign, tells a remarkable story of a Republican Party unwilling or unable to move on from him.

He lost to Mr Biden in 2020 after fuelling near-constant chaos while in the White House, culminating with his supporters carrying out a deadly attack on the US Capitol.

He faces 91 felony charges across four criminal cases, including two indictments for his efforts to overturn the election and a third indictment for keeping classified documents in his Florida home.

In recent weeks he has increasingly echoed authoritarian leaders and framed his campaign as one of retribution.

He has spoken openly about using the power of government to pursue his political enemies.

He has repeatedly harnessed rhetoric once used by Adolf Hitler to say that immigrants entering the US illegally are “poisoning the blood of our country”.

And he recently shared a word cloud last week to his social media account highlighting words like “revenge,” “power” and “dictatorship”.

Republican voters have been undeterred.

“Trump is a Christian. He’s trustworthy. He believes in America. And he believes in freedom,” said 71-year-old Kathy DeAngelo, a retired hospital administrative employee waiting in sub-zero weather to see Mr Trump on Sunday. “He’s the only one.”

On the eve of the caucuses, Mr Trump predicted he would set a modern-day record for an Iowa Republican caucus with a margin-of-victory exceeding the nearly 13 percentage points that Bob Dole earned in 1988.

He also sought to downplay expectations that he would earn as much as 50% of the total vote.

Whether he hits that number or not, his critics note that roughly half of the state’s Republican voters will likely vote for someone not named Trump.

“Somebody won by 12 points and that was like a record. Well, we should do that,” Mr Trump said on Sunday during an appearance at a Des Moines hotel.

“If we don’t do that, let ’em criticise us, right? But let’s see if we can get to 50%.”

“Brave the weather and go out and save America,” he later added.

The temperature in parts of Iowa on Monday could dip as low as minus 26C while snowdrifts were making travel hazardous across the rural state where unpaved roads are common.