Republicans will be able to choose between several candidates to replace Rep. Cory Gardner.
Gardner is challenging Democratic Sen Mark Udall. That leaves an opening in Colorado's Fourth Congressional District, which covers the eastern plains, the southeastern edge of the state and parts of Douglas County.
Republican delegates at a party assembly Friday chose State Sen. Scott Renfroe and Weld County District Attorney Ken Buck to appear on their party's primary ballot.
Weld County Commissioner Barbara Kirkmeyer and former Rhode Island mayor Steve Laffey are expected to make the ballot through another process.
Whoever wins the GOP's June primary will be highly favored to win November's general election because the district is heavily Republican.