The Republican Party was dominant in Colorado as the century began. They had 186,000 more registrants than Democrats and were slightly ahead of unaffiliated voters.
Democrats made an incredible surge in registration just before the Democratic National Convention held in Denver and the Obama election win in 2008. By 2009, Democrats equaled Republicans at one million adherents each.
As Democrats were increasing, unaffiliated registration caught fire, and in 2009, all three parties had one million registrants. But, unaffiliated voter registration tracked more closely to the huge population growth in the state. They are now the dominant group with more than 1.4 million registrants.
Republicans had some modest growth since 2000, but stalled in the late Obama years (2013-2015). Democrats continued modest growth after their 2009 surge and are now the second largest party at 1.1 million and about 40,000 ahead of Republicans.
Unaffiliated voters can now participate in primaries and could have even more influence in the general election. Will they vote in either election?
Open primaries for unaffiliated voters come with a catch