Unable as a Conference to carry out a filibuster in the wake of Sen. Arlen Specter’s (Pa.) party switch, Senate Republicans are eyeing the blue slip as the way to maintain their influence over President Barack Obama’s judicial nominations.

Neither Republican Senators nor conservative advocacy groups were expecting Specter — who had been the ranking member on the Judiciary Committee — to change his long-standing, conservative philosophy on judges. But with a newly diminished minority of 40 seats, GOP Senators remained uncertain as to how the Pennsylvanian’s defection to the Democratic Party would affect the political calculus on judicial nominations going forward, if at all.

“Well, we’re outnumbered, obviously,— Sen. Jim DeMint (R-S.C.) said Wednesday, before adding: “I think we’ve reminded the president we will blue slip judges if Senators from their states disagree. So, we’re still in the game.—

The blue slip policy allows any Senator to put a hold on a president’s judicial selection so long as the nominee hails from that Senator’s home state. Sen. Jeff Sessions (R-Ala.) — once denied confirmation to the federal bench by a Democratic Senate — is expected to take over for Specter as the ranking member on Judiciary, and how he handles the job could help guide the GOP Conference’s strategy on Obama’s federal court picks going forward.

Absent extraordinary circumstances, the Republican Conference would have been hard-pressed to muster a filibuster on one of Obama’s judicial nominees given that Specter professed early on in the 111th Congress that he didn’t favor employing the parliamentary maneuver. But Republicans liked having the tool in their pockets to use as leverage against a powerful Democratic majority.

Sen. Sheldon Whitehouse (D-R.I.), who sits on Judiciary, acknowledged that achieving cloture on an Obama court nominee is somewhat easier now that Specter has shifted allegiances, although he described the committee as a group of “pretty independent folks— and emphasized that he did not expect Specter to all of a sudden reverse his position on judges.

“Presumably every vote helps where cloture’s involved,— Whitehouse said. “Many Republicans have said they would never support cloture on presidential appointees … I suppose this is an extra bit of insurance that we have a better shot of getting through cloture blockades.—

Although, as a Republican, Specter voted with the Democrats on several key issues, he has typically been in the GOP camp when it comes to the federal bench. In early February, Specter told Roll Call, “Qualified means you interpret the law, you don’t act as a super legislature.—

Some key Republican Senators said Wednesday that it is far too early to decide what Specter’s leaving the GOP means for the judicial nominating process. Whether Specter will react more favorably to Obama’s federal court nominees than he otherwise would have — and whether the president will nominate judges who are more liberal now that he has one more Democrat in the Senate — remains to be seen. Obama has vowed to campaign for Specter in his upcoming re-election, a race that influenced the Pennsylvania Senator’s decision to abandon the GOP.

The Committee for Justice, a group that advocates for conservative judges, released a lengthy memo Wednesday lauding Specter’s approach to the judiciary to date and predicted that the Senator’s record would not change now that he is Democrat. Democratic Senate aides reacted similarly, saying they expected Specter to continue to vote with Republicans when it comes to filling out the federal bench.

“With respect to judges, Specter has his own view on things, and I’m not sure how much it’s going to change just because he changed parties,— Senate Minority Whip Jon Kyl (R-Ariz.) said.

Specter said in a statement Tuesday announcing his party switch that he would maintain the independence that has defined his career and would not be a guaranteed Democratic vote: “I will not be an automatic 60th vote for cloture,— he said.

His statement mentioned the Employee Free Choice Act in particular, a pro-labor initiative that would make it easier for workers to organize. Specter voiced his opposition to the proposal earlier this year as he was eyeing a challenge in the Republican primary from conservative former Rep. Pat Toomey. Toomey later entered the race.

One senior Senate Republican aide said the first test for Specter on judges will be an upcoming cloture vote on Dawn Johnsen, Obama’s nominee to head the Office of Legal Counsel in the Justice Department. Specter has voiced serious concerns about Johnsen — and the GOP aide said whether Specter votes for cloture could foreshadow his future approach to Obama’s nominees. Specter said during a press conference Tuesday that he opposed Johnsen’s nomination.

Going forward, some speculated that Specter might agree to end debate on Obama’s judicial nominee, enabling the Democrats to move toward final passage, but then vote against confirmation. In that way, he could claim to maintain his independence without rebuffing Obama. This is a tactic that could be employed by other centrist Democrats who feel politically boxed in by the administration when it comes to the courts.

Republicans are hopeful that Specter will not change from the man who helped usher in President George W. Bush’s Supreme Court nominees — Chief Justice John Roberts and Associate Justice Samuel Alito. Barring that, however, a former Republican aide to the Judiciary Committee said the GOP would have to rely on the blue slip, or loading up bills with time-consuming amendments, should they find an Obama nominee objectionable enough.

Though no Republicans were suggesting Wednesday that nomination battles weren’t in the Senate’s future, Republican Conference Vice Chairman John Thune (S.D.) speculated that Specter would remain allied with his old Conference, at least on this issue.

“He’s got a deep, profound respect for the law. And I think that will shape his judgment when it comes to judicial nominations,— Thune said.