Former U.S. Attorney Pat Meehan (R) announced Monday that he would run for Rep. Joe Sestak’s (D) seat. Sestak is leaving to run for Senate, creating a competitive open-seat race in his southeastern Pennsylvania district in 2010.

“I am formally announcing my candidacy for U.S. Congress because I want to restore integrity to our nation’s capital and ensure that the voice of local voters is heard on critical issues like taxes, jobs, health care, and restoring fiscal responsibility to the federal government,’ Meehan said in his announcement.

Meehan was running in a crowded gubernatorial primary until recently, when he indicated that he was considering a bid for Congress. Although Sestak won re-election by 20 points last cycle, the district had been considered fairly reliable Republican territory until this decade. President Barack Obama won the district with 56 percent of the vote in 2008.

Republicans are optimistic about Meehan’s chances and have cleared the field for the former Delaware County district attorney. Meehan’s would-be primary competition, businessman Steve Welch (R), announced over the weekend that he was switching races to run in Rep. Jim Gerlach’s (R) neighboring 6th district. Gerlach is running for governor in 2010, and there are already two Republicans — state Sen. Curt Schroder and Chester County Recorder of Deeds Ryan Costello — in the race to replace him.