The only Democrat to represent Colorado’s 4th Congressional District in the last 50 years is endorsing Trisha Calvarese’s bid to challenge Republican U.S. Rep. Lauren Boebert’s run for reelection, Calvarese’s campaign announced.

Former U.S. Rep. Betsy Markey, who held the seat for a single term from 2009 to 2011, said in a statement that Calvarese has what it takes to win over the heavily Republican district voters.

“As someone who knows what it takes to flip and represent the great people of Colorado’s 4th district, I am proud to throw my support behind Trisha Calvarese again ahead of the 2026 midterms,” Markey said. “Trisha is young, energetic, and puts in the work to get out and meet people where they are. She will show up and fight every day for Eastern Colorado communities from Loveland to Lamar.”

Markey unseated former U.S. Rep. Marilyn Musgrave, the Republican incumbent, in 2008, the same year Colorado voted for Democrat Barack Obama. She lost her bid for a second term to Republican Cory Gardner, who went on to win a seat in the U.S. Senate in 2014, the same year Markey lost a race for state treasurer.

Calvarese, the 2024 Democratic nominee for the seat, is one of five candidates running in the Democratic primary in the 4th CD, which covers suburban Douglas County and the state’s Eastern Plains.

After winning election twice in the Western Slope’s 3rd Congressional District, Boebert moved into the 4th CD early last year after its five-term incumbent, Republican Ken Buck, announced he wouldn’t seek another term. Although her Democratic opponent outspent her by a wide margin last summer and early fall, Boebert beat Calvarese last November by an 11.6-point margin.

At the same time her campaign announced Markey’s backing, Calvarese unveiled endorsements from more than a dozen current and former state lawmakers and community leaders, including state Senate Majority Leader Robert Rodriguez, D-Denver, state Sen. Jessie Danielson, D-Wheat Ridge, state Rep. Sheila Leider, D-Lakewood, and former Denver 7 meteorologist Mike Nelson.

Among Calvarese’s crop of supporters was former state Sen. Polly Baca, the first Latina to serve in Colorado’s upper chamber and the Democrats’ 1990 nominee in the 4th CD.

“I have gotten to know her from her time in organized labor, especially writing for my friend, the late labor legend, Richard Trumka,” Baca said. “Trisha understands that all working people, regardless of immigration status, deserve respect, dignity, and a voice on the job. She is the best candidate to protect women’s rights, workers’ rights, and our rural communities across Eastern Colorado.”

Calvarese worked as a speech writer for Trumka before the longtime AFL-CIO president died, and then held the same position under his successor, Liz Shuler. When she later worked at the National Science Foundation, Calvarese was a member of the American Federation of Government Employees, the largest federal employee union.

Other Democrats running in the district include John Padora, an engineer making his second run for the seat, and first-time candidate Eileen Laubacher, a retired rear admiral and former National Security Council staffer in the Biden administration, who raised an eye-popping $1.9 million in the three-month period that ended on June 30.