There may be one advantage for the GOP after Sen. Arlen Specter (Pa.) defected to the Democratic Party.

Senate Minority Leader Mitch McConnell (R-Ky.) now leads a leaner, more politically unified Conference and arguably has a freer hand to swing a conservative hatchet at President Barack Obama and Congressional Democrats.

Specter’s recent party switch has certainly created problems for Senate Republicans. But McConnell now can go on offense against the White House and majority Democrats without worrying about vulnerable GOP moderates running for re-election in left-leaning states — as was the case last cycle.

The question is, will the notoriously measured McConnell — who is sensitive to Democratic charges that the GOP has become the “party of no— — transform the sting of Specter’s switch into a political asset? Sort of, said Republican operatives who monitor the Senate and are familiar with McConnell.

“What it does do is allow him to focus less on courting moderate votes, and more time on getting the Republican message out,— one former Senate Republican leadership aide said. “He’s going to have a lot more time to plan Republican counterattacks.—

On Monday, McConnell hinted that he wouldn’t veer too far off the path he forged at the outset of the 111th Congress. That course has been to offer President Barack Obama praise on the few items where Senate Republicans and the White House are in sync — such as the president’s policies on Iraq and Afghanistan — while vigorously opposing him on issues where there is disagreement.

“The point is, we are the loyal opposition. We’re looking for opportunities to work with the administration when they present themselves,— McConnell said. “With regard to the domestic policy, most of what he’s advocated so far, I and most of my Members think, would not be good for the country.—

During the 2008 cycle, Senate Republicans were 49 Members strong and had more actual power to wield. But McConnell was forced to constantly weigh how each decision would affect moderate GOP incumbents running in swing or left-leaning states.

With Specter’s move across the aisle, McConnell’s most imperiled 2010 incumbents are Sens. Jim Bunning (Ky.), Richard Burr (N.C.) and David Vitter (La.). All three Senators hail from states that tilt to the right.

Had Specter remained a Republican, he would have had a delicate balancing act ahead, particularly as a moderate facing a conservative primary challenge from former Rep. Pat Toomey. And Specter would likely have needed McConnell’s help.

“You can put more lead on the target when you’re not worried about your own folks,— one senior Republican Senate aide said.

Current and former Senate GOP leadership aides concede the obvious: There is little advantage to being in the Senate minority when the majority party occupies the White House.

But one of the few perks is the GOP’s ability to present a near-unified front against Democratic priorities. McConnell’s challenge is to define the GOP’s opposition without appearing as if the party is simply trying to obstruct the Democratic agenda.

Specter’s decision left Senate Republicans one seat shy of the ability to sustain a filibuster as a Conference, and Minority Whip Jon Kyl (R-Ariz.) suggested that Republicans need to shift their strategy as a result. Kyl echoed McConnell in saying that Republicans would oppose Obama and Senate Democrats when they disagree with a policy, and offer support and collaboration when they agree.

“We no longer have the votes to hold anything, so I don’t think anybody’s going to properly call us the party of no,’— Kyl said. “If something gets defeated, it will have to be because some Democrats joined in.—

Specter’s departure “changes the environment— for nearly every member of the GOP leadership, said one Republican who works downtown, except possibly for National Republican Senatorial Committee Chairman John Cornyn (Texas).

McConnell and the rest of the leadership can follow their conservative instincts with less concern for the electoral prospects of 2010 incumbents. But Cornyn, who is personally conservative, is courting several GOP moderates to challenge Senate Democrats running for re-election in left-leaning states.

The NRSC chairman also is charged with defending Republican-held open seats in competitive swing states, and he must be careful not to stigmatize GOP Senate candidates. Cornyn’s message, according to some Republican operatives, will be geared toward helping his 2010 candidates win their races.

However, other GOP strategists say Cornyn and Senate Republicans probably won’t make much of a difference on those races — positively or negatively. With Democrats firmly in control of the legislative and executive branches, they said, the GOP’s fortunes will rise or fall depending on how the public perceives Obama as next year’s election approaches.

“The Democrats are in charge,— one Republican political strategist said. “I think this gives us more freedom to say: They own this now.’—