Potential 2010 Senate candidate 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 will make an appearance at a key conservative activists' dinner tonight, perhaps laying groundwork for a campaign.

Toomey will be the keynote speaker at the Pennsylvania Leadership Conference taking place in Harrisburg, Pa. this weekend.

The conference will host what it asserts on its website is a record number of conference attendees in central Pennsylvania, as Toomey mulls a primary challenge to Sen. Arlen Specter (R-Pa.).

Toomey had challenged Specter from the right in 2004, and would again wage a conservative challenge should he run again.