HARRISBURG, Pa. -

Democrats will avoid a primary fight in the race for a soon-to-be-vacant U.S. House of Representatives seat in southeastern Pennsylvania.

Mike Parrish, a Chester County businessman, said Tuesday that he's dropping out of the race and supporting fellow Democrat and Iraq war veteran, Dr. Manan Trivedi.

That leaves Trivedi unopposed for the Democratic nomination in the May 20 primary.

Jim Gerlach, a six-term Republican, is vacating the seat, which takes in parts of Berks, Chester, Lebanon and Montgomery counties.

Lawyer Ryan Costello, a Chester County commissioner, is unopposed for the Republican nomination.

Parrish said he decided that an expensive and contentious Democratic primary fight would risk the party's ability to win the seat in the Nov. 4 election.

Trivedi, a Reading Hospital physician, unsuccessfully challenged Gerlach in 2010 and 2012.