WASHINGTON — Former Pennsylvania Gov. Tom Ridge said today he's not going to challenge Sen. Arlen Specter next year.

Ridge is a moderate Republican who was the nation's first homeland security chief. He said in a statement that his party is facing challenges and he will work with the GOP, but he will not seek the nomination.

A Quinnipiac University poll this week showed Specter and Ridge running about even in a hypothetical general-election race. Party officials have said he was considering a run. Former Republican Rep. Pat Toomey has announced his candidacy for the Senate.

Specter recently split with the Republican Party after four decades to become a Democrat.

Earlier today, Democratic Rep. Joe Sestak says he's considering running.