From Eric Lichtblau's blog at the Times:
Before Tuesday, Mr. Specter had been mildly skeptical of Mr. Holder’s his role in the Marc Rich pardon controversy while withholding judgment on how he would vote. But he let loose on the Senate floor with a speech that compared Mr. Holder to Alberto Gonzales, who was forced to step down as attorney general despite close ties to President Bush, criticizing his "ability to maintain his independence from the president."
In addition to the Rich pardon, Mr. Specter criticized Mr. Holder’s actions in the Wen Ho Lee espionage investigation, the Waco siege, allegations of campaign finance abuse by the Clinton White House, and other matters.
Text from the speech to appear here as soon as it becomes available.
It's not clear where Sen. Specter gets off with this level of no-holes barred attack. But it's fair to say that, for him, the honeymoon's over.