Yesterday, Representative Ryan Costello (R-PA, 6th) announced that he will not seek re-election this year.

Pictured: Rep. Ryan Costello (Source: congress.gov)
The Republican congressman said that a toxic political climate, as well as the recent redistricting in Pennsylvania, led him to his decision.
He represents the Sixth Congressional District, which includes parts of suburban Philadelphia; after the court-ordered redrawing of the congressional map, it will lean more Democrat.
Costello, 41, was first elected in 2014.
Costello filed for re-election last week and if he does not pull his name from the May 15 primary election ballot, the GOP will have only one candidate running for the nomination: attorney Greg McCauley.