Four Republicans are competing to replace Rep. Cory Gardner in Colorado's 4th Congressional District in Tuesday's primary.
Weld County District Attorney Ken Buck, Weld County Commissioner Barbara Kirkmeyer, businessman Scott Laffey and state Sen Scott Renfroe are running in the eastern Colorado district. The winner will be favored to win November's election because the district leans heavily Republican.
Gardner is vacating the seat to challenge Democratic Sen. Mark Udall in November.
Two incumbent Republican congressmen also face primaries.
In the 5th Congressional District in Colorado Springs, retired Air Force officer Bentley Rayburn is challenging Rep. Doug Lamborn.
In the 3rd Congressional District in southern and western Colorado, peach farmer Dave Cox is mounting a longshot challenge to Rep. Scott Tipton.