The news of Pennsylvania Rep. Joe Sestak's intent to primary Sen. Arlen Specter may still be settling in among most Democrats and Republicans, but Sestak himself seems pretty comfortable with his transformation from possible, to all-but certain candidate.

"As important as the President's endorsement is, and who wouldn't want President Obama's endorsement, at the end of the day I don't believe that most voters vote because someone else endorsed someone," Sestak told Greg Sargent.

He's equally undeterred by the possibility that Specter will cut a deal with major unions whereby he supports a compromise on EFCA, and they endorse him. Sestak says he plans to run regardless.

Greg also reports that, according to Sestak, "the Democratic Senatorial Campaign Committee had commissioned a poll testing him running against then-Republican Specter in a general election -- and that it showed Sestak winning."

Of course, a Democratic primary is a much different animal than a general election--but it's still a noteworthy finding.