Only registered Republicans in the state of Iowa can participate in the Republican caucus. Individuals may register to vote as a Republican at the caucus.

Monday 15 January 2024: Iowa Precinct Caucuses. Hours begin at 7:00p CST (0100 UTC). Delegate Selection: Proportional Caucus/Convention. Voter Eligibility: Closed Caucus/Convention.

Precinct Caucuses
Source: 2024 Iowa Republican Caucus Results.
Status: Official. Retrieved: Thursday 20 June 2024.
Included in Nationwide vote.

Republican Party Precinct Caucuses meet in each precinct at 7:00 pm CST. Each Precinct Caucuses chooses the precinct's delegates to the County Convention and conducts a Presidential Poll by secret ballot.

Delegates are proportionally allocated to Presidential contenders based on the statewide vote. Each candidate receives (candidate's statewide vote) × 40 ÷ (total statewide vote) delegates. Round fractions to the nearest whole number. If there are too few delegates allocated, the candidate nearest the rounding threshold receives the additional delegate. If too many delegates are allocated, the candidate furthest the threshold looses a delegate. [Bylaws Article VIII.1]

Precinct Caucuses
Source: 2024 Iowa Republican Caucus Results.
Status: Official. Retrieved: Thursday 20 June 2024.

Trump: 40 delegates × 56,243 ÷ 110,272 = 20.402 delegates. Round to 20.
DeSantis: 40 delegates × 23,491 ÷ 110,272 = 8.521 delegates. Round to 9.
Haley: 40 delegates × 21,027 ÷ 110,272 = 7.627 delegates. Round to 8.
Ramaswamy: 40 delegates × 8,430 ÷ 110,272 = 3.058 delegates. Round to 3.

Iowa's National Convention delegates are bound for the 1st ballot unless only 1 candidate is nominated at the Republican National Convention. In that case, Iowa's delegates are bound to vote for that candidate on the first ballot providing that candidate received votes in the Precinct Caucuses. [Bylaws Article VIII.2]

Saturday 17 February 2024: Republican Party County Conventions convene in each county to choose delegates to the Congressional District Conventions and the State Convention.

Saturday 6 April 2024: Republican Party District Conventions convene in each congressional district to choose the state's district delegates to the Republican National Convention according to the results of the Precinct Caucuses. Each of Iowa's 4 congressional districts is assigned 3 National Convention delegates.

Saturday 4 May 2024: The Iowa State Republican Convention officially convenes. 25 of 40 National Convention delegates are selected according to the results of the Precinct Caucuses.

• The State Convention as a whole chooses Iowa's statewide delegates (10 base at-large delegates plus 15 bonus delegates) to the Republican National Convention.

In addition, 3 party leaders, the National Committeeman, the National Committeewoman, and the chairman of the Iowa's Republican Party, will attend the convention as pledged delegates by virtue of their position.

17 May 2023: Des Moines Register. "... we're heading for a mid-January caucus but it's still very unsettled ... " - Republican Party of Iowa Chair Jeff Kaufmann.

1 June 2023: Iowa Governor Kim Reynods signed HF 716 which states that voters must be physically present at presidential caucuses. 43.91 "Any person voting at a precinct caucus must be a person who is or will by the date of the next general election become an eligible elector...."