Chester County Recorder of Deeds Ryan Costello (R) announced Monday that he is dropping out of the open-seat race in Pennsylvania’s 6th district next year. Costello’s departure from the race leaves four other Republicans vying to replace Rep. Jim Gerlach (R), who is running for governor in 2010.State Rep. Curt Schroder and businessman Steven Welch are now the leading contenders in the GOP primary. Welch had been preparing to run in the open-seat race in the 7th district but switched this fall to run in the 6th instead. Many GOP insiders view Welch as their strongest possible candidate due in part to his ability to put personal resources into the contest. He has loaned his campaign at least $500,000 so far.Howard Cohen, a former aide to ex-Gov. Richard Thornburgh (R), and Patrick Sellers, a local GOP committeeman and fan of Rep. Ron Paul (R-Texas), are also seeking the GOP nomination, and Lower Merion Township Commissioner V. Scott Zelov is considering the race. Schroder and Costello got into the race shortly after Gerlach announced he was leaving to run for governor.In making his announcement, Costello admitted to pa2010.com that he had been unable to gain traction in the race. He also did not indicate that he would endorse one of the other candidates.“It is crucial to our State and Country that the 6th Congressional District remains in the Republican column, and I will enthusiastically support the Republican candidate who wins the 2010 primary,— he said, according to the Web site.