Sen. Arlen Specter's likely challenger in the 2010 Pennsylvania Senate race is gaining ground but still trailing following Specter's switch to the Democratic Party, according to a new poll.

A Quinnipiac University poll showed former Rep. Pat Toomey trailing Specter by 9 points, 37-46 percent, in a hypothetical general election.

That's better than Toomey's showing in a May 4 poll, in which he trailed Specter by 20 points immediately following Specter's party switch...