Colorado has same-day voter registration [CTS 1-2-217.7]. Unaffiliated voters may vote in either the Democratic or Republican primary election, but not both. [CRS 1-7-201(2.3)]. Voters who are affiliated with a major political party may switch their affiliation no later than 29 days before the primary election. State law restricts participation in Party caucuses and conventions to registered Party members [CRS 1-3-101]. Unaffiliated voters are allowed to vote in a party primary without affiliating with the party [CRS 1-7-201(2.3)].

Tuesday 3 March 2020 (presumably): Colorado Primary. Hours end at 7:00p MST (0200 UTC). Colorado votes mostly by mail. Delegate Selection: Winner-Take-Most Primary. Voter Eligibility: Modified Primary.

Primary
Source: Colorado Secretary of State.
Status: Official. Retrieved: Saturday 4 April 2020.
Included in Nationwide vote.

All of Colorado's 37 delegates to the Republican National Convention are allocated to presidential contenders in today's Colorado Presidential Primary. [CRC Bylaws, Art. XIII.A.1.a]

• If one candidate receives a majority of the statewide vote (more than 50% (TBD)), that candidate is allocated all of the delegates.
• If no candidate receives a majority of the statewide vote, each presidential candidate receiving 20% or more of the statewide vote shall be allocated delegates accordingly based on their percentage of the vote total of those candidates who met the 20% threshold. (no mention of what to do if too many delegates are allocated due to rounding)

Primary
Source: Colorado Secretary of State.
Status: Official. Retrieved: Saturday 4 April 2020.

Winner-take-all for Trump.

Precinct caucus attendees must be registered to vote and affiliated with the Republican Party by TBD and must be a resident of their precinct by TBD to be eligible to participate in their precinct caucus.

Saturday 7 March 2020 (presumably): Precinct Caucuses meet in each precinct at 10:00a MST (1700 UTC) to choose delegates to the County Assemblies and District Conventions. Caucuses last about 1.5 hours. There are 2,917 (TBD) precincts.

• There is no formal system applied in the Precinct Caucus to relate the presidential preference of the participants to the choice of the precinct's delegates to the Colorado County Assemblies and District Conventions; (NOTE: It is the District Conventions and the State Convention that will actually elect Republican National Convention delegates to presidential contenders).

Sunday 8 March - Wednesday 1 April 2020: County Assemblies. County Assemblies elect delegates to the Congressional District and State Conventions.

Distict Caucuses choose the 6 National Convention Delegates (3 in each of Colorado's District) according to the results of the Presidential Primary along with the district's delegates to the Colorado State Republican Convention.

Saturday 18 April 2020 (presumably): The Colorado State Republican Convention convenes. The State Convention chooses 13 of 37 delegates from Colorado to the Republican National Convention. Delegate Selection: Delegate Selection Caucus/Convention. Voter Eligibility: Closed Caucus/Convention.

• National Convention Delegates are bound according to the results of the Presidential Primary.

In addition, 3 party leaders, the National Committeeman, the National Committeewoman, and the chairman of the Colorado's Republican Party, will attend the convention by virtue of their position, bound according to the results of the Primary.

Candidates for national convention delegate need not identify the presidential candidate they are pledged to support, but may do so at their option. CRC Bylaws, Art. XIII, §A.3.c.

If a Presidential candidate releases his delegates through public declaration or written notification, the candidate's name is not placed in nomination, or the candidate does not otherwise qualify for nomination under the rules of the Republican National Convention, CRC Chairman shall release ... Delegates ... allocated to that candidate. Such National Delegates released may cast their ballots as each may choose, and the CRC Chairman shall announce the delegation’s vote accordingly. The Chairman shall release the National Delegates by category in the following order, and within category as the Chairman directs: First, Delegates pledged to such candidate; second, the National Committeeman and National Committee Woman; third, unpledged Delegates; fourth, others [CRC Bylaws, Art. XIII.A.1.a]. On any succeeding ballot for President and on all ballots for other purposes the individual delegates are released to cast their ballots as each may choose [CRC Bylaws, Art. XIII.A.1.a].