2024 Colorado's 4th congressional district special election

The 2024 Colorado's 4th congressional district special election was held on June 25, 2024, to fill the vacant seat in Colorado's 4th congressional district. The winner will serve in the United States House of Representatives for the remainder of the 118th United States Congress. The seat became vacant on March 22, 2024, when Ken Buck resigned from Congress.

The 4th district is based in eastern Colorado and the exurbs of Denver, taking in Highlands Ranch, Loveland, and Castle Rock. It is considered a safe Republican district and the most strongly Republican district in Colorado.

Nominees were not chosen via primary election. Instead, each party's nominee was selected by a committee of party leaders and elected officials in the 4th congressional district.

Republican nominee Greg Lopez easily defeated Democratic nominee Trisha Calvarese with 58.4% of the vote.

Republican nomination
The Republican nominee was chosen on March 28, 2024, by a 111-member committee. Two candidates in the election, Holtorf and Lynch, served on the committee.

Nominee

 * Greg Lopez, former mayor of Parker and candidate for governor in 2018 and 2022

Eliminated at convention

 * Ted Harvey, former state senator and candidate for the 6th district in 2008
 * Richard Holtorf, state representative
 * Mike Lynch, state representative and former Minority Leader of the Colorado House of Representatives
 * Scott Melbye, nuclear energy executive
 * Chris Phelen, businessman and former policy advisor to U.S. Senator Kyrsten Sinema
 * Jerry Sonnenberg, Logan County commissioner and former president pro tempore of the Colorado Senate
 * Floyd Trujillo, energy consultant and candidate for U.S. Senate in 2014
 * Peter Yu, mortgage banker, nominee for the 2nd district in 2018, and candidate for U.S. Senate in 2022

Withdrawn

 * Deborah Flora, radio host and candidate for U.S. Senate in 2022 (unsuccessfully ran in the regular primary)

Declined

 * Lauren Boebert, U.S. Representative from the 3rd district (running in regular primary)

Democratic nomination
The Democratic nominee was chosen at a meeting on April 1, 2024.

Nominee

 * Trisha Calvarese, communications professional

Eliminated at convention

 * Karen Breslin, attorney, college professor, and candidate for U.S. Senate in 2022
 * Ike McCorkle, U.S. Marine Corps veteran and nominee for this district in 2020 and 2022
 * John Padora, engineer

Candidates

 * Frank Atwood (Approval Voting), chair of the Approval Voting Party and perennial candidate
 * Hannah Goodman (Libertarian), chair of the Colorado Libertarian Party