Colorado state legislators were sworn in on January 4, 2019, and for the first time since 2012, Democrats gained control of the state Senate. Since Democrats also maintained control of the state House and the governorship, the outcome of the 2018 election made Colorado into a Democratic trifecta. A state government trifecta exists when one political party simultaneously holds the governor’s office and both state legislative chambers.
Seventeen of the Colorado Senate seats were up for election in 2018. Going into the election, Republicans held 18 seats, Democrats held 16, and one seat was held by an independent. Ballotpedia identified six battleground races where the incumbent had last won with less than 55 percent of the vote in 2014. These battleground races took place in Districts 5, 11, 16, 20, 22, and 24. Prior to the election, three of these battleground seats were held by Democrats (one of whom was term-limited in 2018), two by Republicans, and one by an independent (who was also term-limited in 2018). Democrats won all six of the battleground races and shifted the chamber’s partisan balance to 19 Democrats and 16 Republicans.
In addition to Colorado, five other states also became Democratic trifectas as a result of the 2018 elections: Illinois, Maine, Nevada, New Mexico, and New York.