Incumbent Republican Andrew P. Harris, who had represented the district since 2011, ran for re-election.

The 4th district includes parts of Prince George's, Montgomery, and Anne Arundel counties.

Incumbent Democrat Steny Hoyer, the House Minority Whip, who had represented the district since 1981, ran for re-election.

He was elected with 59% of the vote in 2012 against Republican incumbent Roscoe Bartlett, and the district had a PVI of D+4.

Incumbent Democrat Chris Van Hollen, who had represented the district since 2003, ran for re-election.