Republican presidential candidates are out making their final pitch to voters on the last full day of campaigning before the Iowa caucuses.
Three contenders - Mitt Romney, Ron Paul and Rick Santorum - lead the pack ahead of the vote on Tuesday.
But recent polls indicate many Iowans have still not decided who they want to vote for, the BBC reports.
Iowa's ballot is the first contest to pick the Republican who will challenge President Barack Obama for the White House.
The caucuses will involve about 120,000 Iowans gathering in homes, schools and public buildings on Tuesday evening.
Candidates are meanwhile conducting a last-minute flurry of campaign events to win over undecided voters.
The weather in Iowa, which often experiences harsh winters, could be a determining factor in voter turnout.
Ron Paul is said to be the most likely candidate to benefit from poor weather conditions, and consequently, a low turnout, while Mr Romney could see his support rise in fair weather.
Mitt Romney leads in the state, which derailed his last run for the presidency in 2008 amid voter concerns about his Mormon faith and perceived inconsistency on some social issues.
The former Massachusetts governor will win, analysts believe, if the evangelical Christian vote is fragmented across competing conservative candidates.