US presidential candidates are making a final pitch to people in the state of Iowa, where the first votes for party nominations will take place on Monday.
Polls suggest that business tycoon Donald Trump has a lead over Ted Cruz and the other Republican candidates.
But the Democratic race is much tighter, with former US Secretary of State Hillary Clinton just edging ahead of Vermont Senator Bernie Sanders.
Each party’s nominee will contest the presidential election in November.
Over the weekend, the candidates barnstormed the sparsely populated Midwestern state of Iowa in a last-minute attempt to court undecided voters.
Candidates are hoping to triumph in this first electoral test, because victory translates to campaign momentum and increased media coverage.