Moving aggressively to unite behind a top prospect in one of their most vulnerable open seats, Congressional Republicans are set to unofficially kick off the race for Pennsylvania's 15th district tonight by hosting two events for the state lawmaker they want to succeed Rep. Pat Toomey. State Sen. Charlie Dent, described as the "heir apparent" to the party's nomination, will be the featured guest at back-to-back meet-and-greet events at the Capitol Hill Club. National Republican Congressional Committee Chairman Tom Reynolds (N.Y.) is hosting one reception for Dent, sponsored by the U.S. Chamber of Commerce PAC. A separate event is being...