Rep. Jim Gerlach (R-Pa.) announced Monday that he won't seek reelection this year.
Gerlach's decision throws another vulnerable Republican seat into play thanks to a retirement.
Gerlach, 58, said in a statement that "it is simply time for me to move on to new challenges and to spend more time with my wife and family."
“This is a tremendously difficult decision because I have had the opportunity to work with a multitude of dedicated public servants throughout the years," he said.
The news was first reported by PoliticsPA.com.
Gerlach's suburban Philadelphia district went for Mitt Romney by three points in the 2012 election. Gerlach has long been targeted by Democrats, but his district got a little safer on the GOP-drawn redistricting map implemented before the 2012 election.
Gerlach adviser Vince Galko said the congressman won't run for any office in 2014 -- he could have challenged unpopular Gov. Tom Corbett (R) in a primary -- but is "not closing the door in the future."
Gerlach briefly ran in the 2010 primary against Corbett but later decided to run for reelection to his House seat.
Gerlach is the ninth House Republican to announce he won't seek reelection and the fifth from a competitive district. Nearby Rep. Jon Runyan (R-N.J.) has also called it quits.
Such districts are generally much more winnable for the other party when there is an open seat rather than an incumbent seeking reelection.
Only one Democratic House member -- Rep. Jim Matheson (D-Utah) -- has announced he won't seek reelection. Republicans are favored to win that seat.
Potential GOP candidate for the seat include Chester County Commissioner Ryan Costello, former Senate candidate Sam Rohrer and state Sen. John Rafferty. On the Democratic side, businessman and Army veteran Michael Parrish has filed to run.
Updated at 2:24 p.m. This post initially said Runyan was from Pennsylvania. It has been corrected.