What happens when a U.S. senator from Colorado leaves their job midterm (as Michael Bennet may do)
U.S. Sen. Michael Bennet’s decision to run for Colorado governor is prompting a lot of questions about what would happen to the Democrat’s seat should he win the gubernatorial race.
Here’s what the law says, how things have played out in the past and what Bennet has said about his plans.
What Colorado law says
Colorado law hands the governor the power to fill a U.S. Senate vacancy.
The appointment lasts until the next general election, when the rest of the departing senator’s term is up for grabs. If the departure happens in parallel with the general election marking the end of the term anyway, then the election is still for a full six-year term.
Bennet’s current term ends in January 2029. If he wins the 2026 governor’s race, the next general election would be in 2028. That means whoever runs for his seat in 2028 would be seeking a full six-year term in the Senate. (The person appointed to fill Bennet’s vacancy would serve for about two years.)
Colorado law doesn’t specify how long a governor has before they must appoint someone to fill a Senate vacancy. But with Democrats in a narrow minority in the U.S. Senate, there’s a big impetus for the appointment to happen quickly.
The governor isn’t required to appoint someone of the departing senator’s same party to fill the vacancy. But in practice it always happens that way.
How the rest of the country does it
There are more than 35 states that fill U.S. Senate vacancies as Colorado does, by gubernatorial appointment with the seat coming up for grabs at the next general election.
About a dozen states require that a special election be called to fill the seat, with a handful of those letting the governor appoint someone to fill the vacancy until the special election can be held.
Nine states require a gubernatorial appointee to fill a Senate vacancy be of the same party as the vacating senator. As we mentioned above, Colorado isn’t among those nine.
The last time it happened
Bennet was the last person appointed to fill a vacancy in one of Colorado’s two U.S. Senate seats.
That happened in 2009, after then-Sen. Ken Salzar was tapped by then-President Barack Obama to be Interior secretary.
Salazar’s resignation kicked off a major behind-the-scenes influence campaign among the state’s top Democrats aimed at persuading then-Gov. Bill Ritter’s replacement decision. The top contenders included then-Denver Mayor John Hickenlooper, then-Colorado House Speaker Andrew Romanoff, U.S. Rep. Diana DeGette and then-U.S. Rep. Ed Perlmutter.
Despite the roster of big-name Democrats seeking the appointment, Ritter chose Bennet, who at the time was superintendent of Denver Public Schools with little statewide name ID.
The Denver Post reported at the time that Ritter interviewed 15 people for the job.
“He is practical, pragmatic, not ideological. And he is not dogmatic,” Ritter said at the time after announcing Bennet as his pick, according to The Post. “He has an impressive record of bringing people together to find common ground and common-sense solutions to complex problems, and of turning around troubled public and private enterprises and leaving them far stronger than he found them.”
Bennet, a relative unknown who had never held elected office, was seen as an unconventional choice, especially given Colorado’s swing-state status at the time.
But Bennet went on to beat Romanoff in the 2010 Democratic primary and then beat Republican Ken Buck in the general election that year. Bennet easily won reelection in 2016 and 2022.
What Bennet has said about his plans
Bennet will remain in the Senate while he campaigns for governor.
If he wins the race, he could immediately resign and let Gov. Jared Polis select his replacement. But Bennet says he plans to hand pick his successor himself.
“I will appoint my replacement if I win,” he told reporters. “I will say that we have an incredible abundance of talent in this state.”
The most obvious choice would be one of Colorado’s U.S. representatives. Democrats Joe Neguse, Jason Crow and Brittany Pettersen are atop the list and all appear to be interested. Colorado has never had a Black senator (Neguse is Black) or a woman senator.
When asked by The Colorado Sun this week, Polis didn’t deny that he’s interested in the position. He didn’t hint at whether he wanted the job, either.
“Gov. Polis is focused on running through the tape for the overwhelming number of Coloradans from across the state who supported him to serve as their governor until January 2027,” a spokesman said. “Gov. Polis will keep delivering real results … and is not focused on anything else.”
Others are likely to jockey for the position, too. (DeGette isn’t in the conversation, at least not yet.) And there’s a chance Bennet could follow in Ritter’s footsteps and appoint a dark horse to replace him.
Bennet hasn’t said much yet about his thinking on whom he might appoint to fill his seat. He told 9News that he “could make the argument both ways” that he should appoint a caretaker to fill the vacancy through the end of his current term or someone to take on the position long term.
“I was appointed to this seat,” he told 9News. “It matters a lot to me who’s in it.”