Donald Trump and his Republican rivals are making last-ditch pitches to win support in Iowa, hours before voters in the state will kick-off the 2024 race for the White House.
Candidates are holding final events, but frigid conditions have complicated the last days of campaigning.
A resounding victory in Iowa would cement Mr Trump’s frontrunner status.
His rivals, meanwhile, are seeking to establish themselves as the main alternative to the former president.
Republican voters will meet at one of more than 1,500 caucus locations around the Midwestern state on Monday night to state their preferred presidential candidate. All of the candidates have urged voters to brave the extreme cold, as temperatures are forecast to fall as low as -30C (-20F), so they can have their say in the contest amid fears the weather could harm turnout.
The race will then move state by state before an eventual nominee is selected to almost certainly challenge Joe Biden in November’s general election.
The closely watched poll showed Nikki Haley, the former US ambassador to the UN, had moved into second place after gaining momentum in recent days.
Florida Governor Ron DeSantis, who has invested large amounts of resources into Iowa, had slipped to third place. Mr DeSantis will face pressure to drop out if he performs poorly on Monday and the result could prove critical for his campaign.
