Former U.S. Rep. Tom Tancredo on Monday formally endorsed state Rep. Dave Williams to represent Colorado’s 5th Congressional District, calling the Colorado Springs Republican a “proven champion” on critical issues.

Williams is one of four Republicans challenging eight-term U.S. Rep. Doug Lamborn in the GOP primary in the heavily Republican district, which covers most of El Paso County.

“The best thing Colorado can do in CD 5 is dump Doug Lamborn and elect Dave Williams to fight for us,” Tancredo said in a statement released by Williams’s campaign.

“On every issue that matters, from securing our borders to stopping out of control spending, Dave Williams has been a proven champion who will never sell us out or give in to the failed establishment leadership in both parties. Congress desperately needs more real leaders like Dave Williams, so please join me in supporting his campaign right away.”

A spokeswoman for Lamborn’s campaign declined to comment.

Tancredo, who whose fifth and final term in the U.S. House of Representatives from 2007-2009 overlapped with Lamborn’s first term, told Colorado Politics that he has enthusiastically endorsed one of Lamborn’s Republican challengers every time the incumbent has faced a primary. Tancredo ran for president in 2008 and later ran for governor three times, including in 2010 on the American Constitution Party ticket.

Williams trumpeted Tancredo’s backing in an email to voters on Monday, the day before El Paso County Republicans hold precinct caucuses on Tuesday night.

Said Williams: “He knows I won’t back down in support of our values, and I will always fight tooth-and-nail to save our country from the radical left and the weak Republicans who give them free rein.”

Tancredo was an early endorser of U.S. Rep. Lauren Boebert more than two years ago, when few thought the Silt restaurant owner had a chance of unseating five-term U.S. Rep. Scott Tipton in the 3rd Congressional District’s 2020 Republican primary. This cycle, Tancredo has thrown his support behind U.S. Senate candidate Gino Campana, 7th Congressional District candidate Laurel Imer and 8th Congressional District candidate Lori Saine, all Republicans.

Williams is the only GOP candidate in the 5th CD who is seeking a spot in the June 28 primary solely through the caucus and assembly process. The others, including Lamborn, are either hoping to petition their way onto the ballot or pursuing both routes.

Candidates who attempt to qualify by assembly must win support from at least 30% of the delegates at the April 8 district assembly to qualify for the ballot. Petitioners need at least 1,500 valid signatures from fellow party members and have until March 15 to submit them. Lamborn turned in his petitions on Feb. 17 and could learn whether he’s qualified for the ballot by sometime next week.

The other Republicans running for the seat are Navy veteran Rebecca Keltie, who ran last cycle as a third-party candidate; business owner Andrew Heaton; and activist Christopher Mitchell. The Democrats running are first-time candidates Michael Colombe, Jeremy Dowell, Santiago David Goenaga-Torres and Orlando Avion. Four independent candidates have also filed to run in the district.