This story was produced as part of the Colorado Capitol News Alliance. It first appeared at coloradosun.com.
The crowded Republican primary race for Colorado governor received a major jolt in recent days.
State Sen. Mark Baisley, a Woodland Park Republican, filed Monday to leave the race to run instead for U.S. Senate.
“With my campaign staff — we’ve talked about it for about three weeks,” he said in an interview with a conservative podcaster announcing his decision. “My focus is now on the U.S. Senate, where I frankly feel more suited.”
Baisley faces an uphill battle in trying to win the Senate race. He’ll have to start fresh on fundraising and national Republicans have signaled they plan to ignore Colorado’s Senate race this year in favor of more competitive states.
On the flip side, Baisley will likely have a much better chance of making it to the general election as a Senate candidate, where the GOP has struggled to find experienced politicians to try to flip the seat currently held by Democratic U.S. Sen. John Hickenlooper.
Separately, former U.S. Rep. Greg Lopez, another Republican gubernatorial candidate, left the GOP last week to become unaffiliated. He’s still running for governor.
“Both parties raise money better than they solve problems,” Lopez said in a video announcing his decision. “They divide better than they listen.”
Lopez said he is not changing his values as he leaves the GOP, but rather “changing who I answer to.”
Leaving the GOP may make it easier for Lopez to get on the ballot. As a Republican, he would have needed to collect support from Republican insiders through the caucus or assembly process or gather 1,500 signatures from voters in each of the state’s eight congressional districts to make the primary ballot.
As an unaffiliated candidate, he will only need to collect 1,000 signatures from voters in each of the state’s eight congressional districts to make the general election ballot.
Lopez was previously a Democrat, becoming a Republican in the early 1990s while he was serving as mayor of Parker. He is on his third consecutive run for governor after losing in the Republican primaries in 2018 and 2022.
Lopez served as the U.S. representative for the 4th Congressional District for a few months in late 2024 and early 2025 following the midterm resignation of Republican U.S. Rep. Ken Buck.
Even without Lopez and Baisley, there are still plenty of Republicans running to be Colorado’s next governor. The GOP candidate list includes state Sen. Barbara Kirkmeyer, podcaster and election conspiracy theorist Joe Oltmann, and Marine veteran and self-described humanitarian Victor Marx.
Current Gov. Jared Polis, a Democrat, cannot run for reelection in 2026 because of term limits. He won reelection in 2022 by nearly 20 percentage points. He secured his first term in 2018 by 10 points.
Colorado has not elected a Republican governor since 2002, when Gov. Bill Owens secured a second term.
Two prominent Democrats are running to replace Polis: U.S. Sen. Michael Bennet and Colorado Attorney General Phil Weiser.
The Democratic and Republican primaries for governor will be held in June.
