Tuesday 17 March 2020 (presumably): Illinois Primary. Hours reportedly 6:00a-7:00p CDT (1100-0000 UTC). Delegate Selection: Combined Selection Statewide: Winner-Take-All, District: Loophole Primary. Voter Eligibility: Open Primary.

Primary
Source: Illinois State Board of Elections.
Status: Official. Retrieved: Wednesday 27 May 2020.
Included in Nationwide vote.

All 67 of Illinois' delegates to the Republican National Convention will be bound to Presidential Candidates based on the results of today's Illinois Presidential Primary.

• 54 National Convention District delegates are elected in a so-called "Loophole" primary (a Delegate Selection Primary combined with an Advisory "beauty contest" presidential preference vote). Each candidate for [District] delegate ... must file a Statement of Presidential Preference supporting a specific presidential candidate, or a statement that he/she intends to run uncommitted [SBE No. P-1E]. District delegates are directly elected by the voters and individually listed on the ballot with their presidential preferences indicated.
• 10 National Convention Statewide Delegates are bound winner-take-all to the candidate receiving the largest number of votes statewide. These delegates do not appear on the ballot and are chosen at the State Convention.
• The 3 party leaders, the National Committeeman, the National Committeewoman, and the chairman of the Illinois Republican Party, will attend the convention, by virtue of their position, bound winner-take-all to the candidate receiving the largest number of votes statewide.

Primary
Source: Illinois State Board of Elections.
Status: Official. Retrieved: Friday 17 July 2020.

Primary
Source: Illinois State Board of Elections.
Status: Official. Retrieved: Wednesday 27 May 2020.

Delegates are bound for the 1st ballot at the National Convention.

Thursday 11 June - Saturday 13 June 2020 (presumably): The Illinois Republican Party State Convention convenes in Peoria to choose the 10 statewide delegates according to the results of the primary.