Sen. Arlen Specter caught a break today: Tom Ridge, the popular former congressman and governor, announced he won’t run for the Senate. Republican sources familiar with the situation in Pennsylvania tell me that Rep. Jim Gerlach remains a potential candidate and there may be others “who emerge.”

But Specter is still having problems on his side of the aisle. Politico reports:

Sen. Arlen Specter (D-Pa.) may not regain his three decades of seniority even if he wins his Senate seat as a Democrat, robbing him of a key argument he’s making in his 2010 reelection campaign.

After the Senate dealt a major blow to Specter Tuesday night by making him the junior-most senator on five committees, Specter has insisted he had an agreement with Senate Majority Leader Harry Reid (D-Nev.) that he would be treated in the future as if he were elected as a Democrat in 1980. If Specter regains this seniority that was stripped earlier this week, it would significantly boost his influence in the chamber and put him in critical committee positions that would allow him to shower his home state with goodies.

But several Senate Democrats signaled Thursday that Specter may get no special treatment to keep his seniority if he’s serving in the next Congress, which begins in 2011.

Senate Majority Leader Dick Durbin (D-Ill.) on Thursday voluntarily gave up a Judiciary subcommittee to Specter. But asked if the more senior Specter should leapfrog him in the Appropriations Committee and take his gavel of a powerful subcommittee, Durbin said, “The answer in a word, ‘no.’”

Could it be that his new colleagues don’t value his company all that much? Really, from their perspective all they have gotten out of his defection so far is heartburn. Specter voted against the budget and Durbin’s own cram-down mortgage bill. He’s a gaffe machine and a shaky vote on other big ticket items. Why wouldn’t they want a more reliable and loyal Democratic senator? Well, they are surely acting like they would.