[Update 2: After posting the prior update about Specter being given a subcommittee chairmanship, ultra-liberal Democratic Senator Pat Leahy (VT) is at least temporarily disrupting that deal.]

[Update: Two days after stripping Specter of his seniority, the Democrats then gave him the chairmanship of the Crime and Drugs subcommittee of the Judiciary Committee. This appears to be in part a response to a likely Democratic primary challenge to Specter, as I predicted in the note below.]

Here’s a fascinating story from the WSJ’s John Fund:

Nobody Likes a Turncoat

Senate Democrats finally found an entitlement program they dislike so much that they voted to eliminate it last night. No, it wasn’t a budget vote to shrink the size of government. It was the deal that Senator Arlen Specter cut with Majority Leader Harry Reid to preserve Mr. Specter’s committee seniority despite his move from the Republican Party to Democratic Party. On NBC’s “Meet the Press” Sunday, Mr. Specter had called his seniority an “entitlement” he deserved.

“I was elected in 1980. I think [keeping my seniority] is not a bribe or a give for something extraordinary,” he said. “I’ll be treated as a Democrat as if I was elected as a Democrat.”

Not so fast. Resentful Democrats went on the warpath against Mr. Reid’s offer to treat Mr. Specter as if he had been a Democrat since 1980 – an arrangement that could make Mr. Specter a committee chairman if he wins re-election next year. Senate Democrats effectively agreed by voice vote last night to strip Mr. Specter of his seniority – avoiding a roll-call vote that would have revealed exactly who his adversaries inside the Democratic caucus are. Mr. Specter will now be listed as the most junior member on the Judiciary Committee, meaning he’ll be last in line for questioning whomever President Obama appoints to fill the Supreme Court vacancy. That’s a big comedown from his role as chairman during the confirmation battles surrounding John Roberts and Sam Alito in 2005.

With the loss of seniority, there is almost no way Mr. Specter can become even a subcommittee chairman assuming he wins a sixth term next year. It robs him of a major selling point he was planning to use to convince Pennsylvania voters to return him to office. Mr. Specter will argue that Democrats could always revisit the issue of his seniority after the 2010 elections, but the precedents aren’t good. In 2003, Democrats enticed former Senator Frank Lautenberg back into public life to save the New Jersey seat held by scandal-tarred Bob Torricelli. Mr. Lautenberg kept the seat for his party as the last-minute Democratic nominee, but was relegated to junior roles on committees even though he had 18 years of prior service in the Senate.

It seems that Mr. Specter, a master political operator and opportunist, has been outfoxed. He may have an easier time winning renomination in a Democratic primary, but his new party has now stripped him of his most precious Senate asset – his seniority.

What could be better than this?

This is the worst thing that could have happened to Arlen Specter, and a nice gift to Republicans and Pat Toomey in their quest to defeat Specter in 2010. Indeed, it even opens the door a little wider to the possibility of a primary challenge to Specter in Pennsylvania, not just because Specter will have that much less clout, but also because his snubbing by the Democrats may cause him to vote slightly more often with the Republicans than he otherwise might have.

Republican leaders in the senate must be laughing out loud and thinking to themselves “What did you expect, Arlen? They’re Democrats and they’re politicians!”