Colorado's 4th district is 72.9% urban, consisting of the eastern portion of the state and including the cities of Castle Rock and Parker. The district is almost entirely white (91.96%) with some hispanic residents (22.24%).

The Democratic candidate is Karen McCormick, a veterinarian and the daughter of a Navy pilot. The Republican candidate and incumbent is Ken Buck, who has served the district since 2015. He was previously the district attorney for Weld County.

This district generally votes Republican, with a Republican winning each of the last three Congressional elections by at least 20 percentage points (two of those elections were Buck) and the Republican presidential candidate receiving more votes than the Democratic candidate in each of the last five presidential elections. In 2016, the district voted in favor of Buck by 31 points and voted in favor of Trump over Clinton by 23 points.