In the past Colorado has held party caucuses for parties to nominate their preferential presidential candidate.
In 2016 Colorado voters approved proposition 107 which eliminates caucuses for a Presidential Preference Primary.
The 2020 presidential primary will allow voters to choose any candidate of their preference. Making it an "open primary."
However, the Supreme Court has ruled against open primaries in Alaska, Washington and California which would have allowed voters to choose candidates from any party for any office.
They ruled that parties have the right to set up their own internal rules, sighting the first amendment right of association.
In my 'supreme opinion' this is bogus, citizens also have the right of association.
This ruling forces voters to reregister under a certain party's banner in order for them to be allowed to "associate" with whichever candidate they wish to "associate" with.
Furthermore, in my "supreme opinion" states and parties that have closed caucuses or primaries are practicing divide and conquer strategies that allows the "party to make the people" instead of the "people make the party."
We still don't know the date of the Colorado presidential primary, the Governor and Secretary of State have until August 30, 2019 to decide the date. But the Colorado 2019 Elections Calender assumes the primary will be on March 3, 2020.
On November 4th candidates may begin circulating petitions to be on the ballot.
December 24, 2019 is the last day for a "major" political party to submit their request to the Secretary of State to provide a place on the presidential primary ballot to vote to send a noncommitted delegate to the political party's national convention.