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 3 February 2020: Iowa Precinct Caucuses. Hours begin at 7:00p CST (0100 UTC). Delegate Selection: Proportional Caucus/Convention. Voter Eligibility: Closed Caucus/Convention.

Precinct Caucuses
Source: Republican Party of Iowa.
Status: Official. Retrieved: Thursday 13 February 2020.
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]

Precinct Caucuses
Source: Republican Party of Iowa.
Status: Official. Retrieved: Thursday 13 February 2020.

Trump: 40 delegates × 31,421 ÷ 32,345 = 38.857 delegates. Round to 39.
Weld: 40 delegates × 425 ÷ 32,345 = 0.526 delegates. Round to 1.

It is likely that only one candidate will have his name formally put in nomination and, under Iowa rules, Weld will lose his 1 delegate on the floor of the National Convention.

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 14 March 2020: Republican Party County Conventions convene in each county to choose delegates to the Congressional District Conventions and the State Convention.

24 March 2020: Due to the COVID-19 pandemic, the State Central Committee, in an emergency conference call, voted unanimously to mail paper ballots to all district delegates instead of holding district conventions.

Saturday 25 April 2020: 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 13 June 2020: 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.