U.S. House Speaker Mike Johnson on Friday formally endorsed Greg Lopez, the Republican nominee in Colorado’s June special election to fill the remainder of former U.S. Rep. Ken Buck’s term.

Calling Lopez “a strong voice to represent Colorado’s 4th District, Johnson said that he’s “proud to give him my full and total endorsement.”

“Greg is a man of faith and I know he’ll work diligently to serve with honor and dignity through the remainder of this term,” Johnson said in a statement released by Lopez’ campaign, adding that he looks forward to working with the fellow Republican.

Lopez, a former Parker mayor and two-time gubernatorial candidate, faces Democrat Trisha Calvarese in the June 25 election, which will take place simultaneously with Colorado’s primary election.

Libertarian Hannah Goodman, the minor party’s state chair, and Approval Voting Party nominee Frank Attwood will also appear on the ballot.

Buck, a five-term Republican from Windsor, resigned from Congress in March, triggering a special election to fill a vacant House seat for only the second time in state history.

Covering Douglas County, Loveland and the Eastern Plains, the sprawling 4th CD is the most reliably Republican seat in the state. Its voters tilted toward former President Donald Trump by nearly 20 points in the 2020 election.

Lopez pitched himself as a “placeholder” candidate, arguing that his appearance on the ballot wouldn’t tip the scale toward any of the GOP primary candidates running for full terms in the district.

Six Republicans made the primary, including U.S. Rep. Lauren Boebert, former state Sen. Jerry Sonnenberg of Sterling, state Reps. Richard Holtorf of Akron and Mike Lynch of Wellington, former talk radio host Deborah Flora and business consultant Peter Yu.

Serving her second term representing the Western Slope-based 3rd Congressional District, Boebert moved across the state into Buck’s district at the beginning of the year after the incumbent announced last fall that he wouldn’t seek reelection.

Calvarese is in a three-way primary for the Democratic nod with Marine veteran Ike McCorkle, who ran against Buck in 2020 and 2022, an engineer and addiction recovery advocate.

Lopez said in a statement that he is honored to receive Johnson’s endorsement.

“Speaker Johnson is a man of faith and no one has a tougher job than he does, guiding Republicans through an incredibly slim majority,” Lopez said. “I look forward to joining Speaker Johnson in Washington and providing an additional voice and vote for conservatives.”

Johnson was elected speaker in October after the House GOP spent weeks struggling to pick a successor to former U.S. Rep. Kevin McCarthy, the California lawmaker who lost the gavel when eight Republican House members — including Buck — voted to remove the speaker midsession.

Lopez is the fourth Colorado congressional candidate Johnson has endorsed this year.

In January, he threw his support behind Boebert shortly after she announced her move into the new district. He has since made endorsements in two other primaries, backing Americans for Prosperity executive Jeff Crank in the El Paso County-based 5th Congressional District and state Rep. Gabe Evans, R-Fort Lupton, in the toss-up 8th Congressional District, which stretches from suburbs north of Denver to Greeley.

Crank is running against Colorado Republican Party Chairman Dave Williams in the heavily Republican 5th CD, which is held by retiring U.S. Rep. Doug Lamborn. Evans is running against former state Rep. Janak Joshi, R-Colorado Springs, for the chance to challenge first-term Democratic U.S. Rep. Yadira Caraveo in the nearly evenly divided 8th CD.

Primary and special election ballots go out to voters on June 3 and are due back to county clerks on June 25.