Former Rep. Pat ToomeyPatrick (Pat) Joseph ToomeyOvernight Defense: Pick for South Korean envoy splits with Trump on nuclear threat | McCain blasts move to suspend Korean military exercises | White House defends Trump salute of North Korean general WH backpedals on Trump's 'due process' remark on guns Top GOP candidate drops out of Ohio Senate race MORE (R-Pa.) has officially announced that he will take on Sen. Arlen Specter (R-Pa.) in the Republican primary.

Toomey made the announcement in a video to on his campaign's new website, ToomeyForSenate.org.

"I am running for the U.S. Senate because I believe the economic stakes for our country have never been higher," Toomey said. "The people of Pennsylvania deserve the very best from their leaders in Washington