In the 2014 midterm, which saw Democrats win a handful of House seats nationally but lose control of the U.S. Senate, Colorado had slightly more than 2 million voters participate. Statewide voters split their tickets, reelecting Democrat John Hickenlooper as governor by 68,000, but exchanging incumbent U.S. Senator Mark Udall for Republican Cory Gardner by 40,000 votes.
There are 3.2 million voters registered, 348,000 more since the 2014 midterm. If about a similar 71 percent turnout, 2.3 million voters will cast ballots. If the enthusiasm that has been registered in some polls is correct, the vote could reach 2.5 million.