Democrat Al Franken could become the key to a veto-proof majority after the announcement by Republican Senator Arlen Specter (R-PA) that he is switching parties.
Franken, a former Saturday Night Live writer and performer, is in a legal battle over the Minnesota Senate seat he won by a hair last November. Incumbent Republican Norm Coleman continues to battle the decision in court, and Franken will not be seated until that challenge is exhausted, Democratic leaders have said.
In an e-mail soliciting funds for the Democratic Senatorial Campaign Committee, DSSC Chairman Bob Menendez of New Jersey, warned that Coleman would probably "dig in his heels and fight even harder to deny us that filibuster-proof 60th seat."
There have been 56 seated Democrats, the un-seated Franken, and two independents, Bernie Sanders of Vermont and Joe Lieberman of Connecticut, who caucus with the Dems.
Specter was one of only three Republicans in the Senate to vote for President Barack Obama's economic stimulus package, a move likely to have meant a tough re-election race.