Democrats close in on filibuster-resistant margin

Sen. Arlen Specter's party switch puts the Democrats within grasp of a 60-seat majority and the first filibuster-resistant margin since the Carter administration three decades ago.

Democrats were the last party to reach that critical mark in the 95th Congress of 1977-1979, when they held 61 seats against 38 Republicans and one independent.

Under Senate rules, a single senator can object to consideration of a bill, in which case it takes a 60-vote supermajority to bring a bill to the floor or end debate so a final vote can be taken.

Specter, currently in his fifth term as a Republican, would become the 57th Senate Democrat. Two independents, Bernie Sanders of Vermont and Joe Lieberman of Connecticut, are usually reliable votes for the Democrats.

The crucial 60th vote would be Al Franken of Minnesota, who has maintained a 312-vote lead over incumbent GOP Sen. Norm Coleman during a lengthy recount process. After several court rulings in Franken's favor, Coleman has appealed to the Minnesota Supreme Court.