From my article over on the home page:

“This race is now much more interesting and competitive,” says Larry Sabato, director of the Center for Politics at the University of Virginia. “Toomey would have beaten Specter like a drum, given this year’s environment. Sestak can be far more competitive. However, my sense is that this is a GOP year in Pennsylvania. Tom Corbett, the gubernatorial nominee, should help Toomey, and there will be a great deal of straight-ticket voting in the fall. But it’s early, and some caution is in order.”
Defining Sestak as a classic left-progressive early on is a key goal, Toomey strategists tell National Review Online. “In my mind, it’s going to be a question of who brands whom first,” observed Charlie Gerow, a Republican political consultant, to the Philadelphia Inquirer. “It will all turn on what happens in the relatively near future.
Unlike Specter, who flailed trying to peg Sestak as a weak leader and ran negative ads questioning Sestak’s Navy record, Toomey is determined to make the candidates’ positions the topic of conversation. “I will need to communicate a very clear contrast between Joe and myself,” Toomey says. “Joe, by virtue of his record, is a Nancy Pelosi liberal. While I am confident that Pennsylvania does not want to elect a San Francisco liberal to the United States Senate, I know that I have to keep barnstorming the state to make my case.”

More here. Below is the pair’s health-care debate from September: