U.S. Rep. Ryan Costello, a Republican in a competitive district based in Chester County, said he would file petitions Tuesday to run in the district. However, when asked Monday, he did not firmly say he was running for re-election. Costello has been a vocal critic of the new map, which changes his district significantly. If he were to file his petitions but drop out up to 85 days before the election, state Republicans could name a replacement on the ballot.