U.S. Rep. Diana DeGette on Thursday endorsed state Rep. Yadira Caraveo in the Democratic primary for the Colorado’s new 8th Congressional District, calling the Thornton pediatrician’s candidacy “historic.”

The Denver Democrat is the first member of Colorado’s congressional delegation to make an endorsement in the hotly contested, four-way primary for the northern Front Range seat, which covers portions of Adams, Weld and Larimer counties and is considered the state’s most evenly divided congressional district.

“As a pediatrician and state legislator, Dr. Caraveo knows how to have tough conversations and take on tough fights — and it’s long past time for Coloradans to elect our first Latina U.S. representative,” DeGette said in a statement. “I look forward to working with Dr. Caraveo in Congress to stabilize our economy and lower health care costs for Coloradans, take on climate change and defend every American’s right to vote.”

Caraveo is competing for the nomination in the new district against Charles “Chaz” Tedesco, nonprofit consultant Johnny Humphrey and former Commerce City Councilman Steve Douglas.

First elected to represent the Denver-based 1st Congressional District in 1996, DeGette, a civil rights attorney and former state lawmaker, is the dean of Colorado’s congressional delegation and is seeking a 14th term this fall in the heavily Democratic district. A year ago, she was one of nine House managers who prosecuted former President Donald Trump’s second impeachment trial in the Senate, which ended in an acquittal.

Caraveo said in a statement that she was honored to receive DeGette’s support.

“Rep. DeGette is a long-time voice for Colorado families, and I look forward to joining her in Congress and fighting big fights for working Coloradans,” she said.

Adams County Commissioner Eva Henry, a Tedesco supporter, told Colorado Politics that the endorsement from one of Denver’s leading Democrats might not carry as much weight in neighboring Adams County, considering the long history of disputes and confrontations between the two local governments.

“DeGette’s move is once again Denver interfering with Adams County politics,” she said in a text message.

Elana Schrager, Caraveo’s campaign manager, dismissed Henry’s objection in an email to Colorado Politics.

“Rep. DeGette’s endorsement emphasizes the widespread support for Dr. Caraveo across Colorado and the strong momentum behind her campaign,” Schrager wrote. “From the moment she launched her campaign, Dr. Caraveo has made it clear that she is focused on bringing communities across the 8th Congressional District together so she can work with people to solve problems and be a strong voice for families in Adams, Weld, and Larimer counties.”

The road to Colorado’s June 28 primary kicks off this week with precinct caucuses, the first step in a delegate-selection process that culminates in a series of party assemblies at the county, district and state levels. Candidates who are petitioning into the primary have until March 15 to turn in their signatures.

The Democrats running in the 8th CD are each taking both routes. For those the candidates submit the required number of petition signatures from fellow party members — 1,500 are needed for congressional candidates — it’ll take the support of 10% of delegates to the congressional district assembly to win a berth in the primary. Otherwise, candidates need 30% support from delegates to make the ballot.

The Republican candidates are state Sen. Barbara Kirkmeyer, Weld County Commissioner Lori Saine, Thornton Mayor Jan Kulmann and first-time candidates Giulianna “Jewels” Gray and Tyler Allcorn.

Editor’s note: This story has been updated with comments from Adams County Commissioner Eva Henry and Elana Schrager, state Rep. Yadira Caraveo’s campaign manager.