Arlen Specter's vote for the stimulus bill proved to be one of his final acts as a member of the Republican Party. But at a fundraiser for the Pennsylvania senator tonight, Vice President Joe Biden said it was more significant than that.

"Without Arlen having convinced two of his Republican colleagues to change their vote and vote for the stimulus package, we would probably be in a depression," he said in Pittsburgh tonight. "The fact of the matter is we would not be about to even begin the kind of recovery that we are about (to begin), that we want, were it not for the fact that Arlen Specter put his career on the line. I owe him. The country owes him."

Specter returned praise, calling his former colleague "the most influential and powerful vice president in our history." He also dwelled on the stimulus vote, calling it the most important of the 10,000 he's cast in his decades in the Senate.

"When I cast that vote, I in effect joined the President Obama team," he said.

Biden joined Specter at the Allegheny County Democratic Committee's annual Kennedy Lawrence Dinner. He also spoke at a separate fundraiser specifically for Specter, who faces both a potentially tough primary and general election challenge in 2010.