Donald Trump has won the Iowa caucuses, a crucial victory at the outset of the Republican primary that reinforces the former president’s bond with his party’s voters.

The success comes despite his extraordinary legal challenges which could complicate his bid to return to the White House.

The magnitude of Mr Trump’s success is still unclear, but the former president’s supporters endured a historic and life-threatening cold snap to participate in caucus meetings at schools, churches and community centres across the state.

The results are just the first in what will be a months-long effort for Mr Trump to secure the Republican nomination for a third consecutive time.

It sends an unmistakable message to the Republican Party that the nomination is Mr Trump’s to lose.

Former UN Ambassador Nikki Haley and Florida governor Ron DeSantis are Mr Trump’s most prominent primary rivals.

They are aiming for a second-place finish in Iowa that would give them at least some momentum heading into future races.

Both are already pivoting their focus with Ms Haley poised to compete vigorously in New Hampshire, where she hopes to be more successful with the state’s independent voters heading into the January 23 primary.

Mr DeSantis is heading straight to South Carolina, a conservative stronghold where the February 24 contest could prove pivotal, before going to New Hampshire.

Iowa is an uneven predictor of who will ultimately lead Republicans into the general election. George W Bush’s 2000 victory was the last time a Republican candidate won in Iowa and went on to become the party’s standard-bearer.

Mr Trump has spent much of the past year crafting a far more professional organisation in Iowa than the relatively haphazard effort he oversaw in 2016, when Texas senator Ted Cruz carried the caucuses.

His team paid special attention to building a sophisticated digital and data operation to regularly engage with potential supporters and ensure they knew how to participate in the caucuses.

For months, the former president predicated a commanding Iowa victory with a 30 or 40-point blowout that he argued would render the rest of the primary essentially unnecessary.

His aides have privately focused on meeting or beating Bob Dole’s nearly 13-point win in 1988, the largest margin of victory ever in a contested Iowa Republican caucus.