Glenn Greenwald: What happened to the Senate's "60-vote requirement"?

Every time Congressional Democrats failed this year to stop the Bush administration (i.e., every time they "tried"), the excuse they gave was that they "need 60 votes in the Senate" in order to get anything done. Each time Senate Republicans blocked Democratic legislation, the media helpfully explained not that Republicans were obstructing via filibuster, but rather that, in the Senate, there is a general "60-vote requirement" for everything.

How, then, can this be explained?

The Senate confirmed Michael B. Mukasey as attorney general Thursday night, approving him despite Democratic criticism that he had failed to take an unequivocal stance against the torture of terrorism detainees.

The 53-to-40 vote made Mr. Mukasey, a former federal judge, the third person to head the Justice Department during the tenure of President Bush . . . Thirty-nine Democrats and one independent [Bernie Sanders] opposed him.

Beyond that, four Senate Democrats running for President missed the vote, and all four had announced they oppose Mukasey's confirmation. Thus, at least 44 Senators claimed to oppose Mukasey's confirmation -- more than enough to prevent it via filibuster. So why didn't they filibuster, the way Senate Republicans have on virtually every measure this year which they wanted to defeat?