Updated: Jan. 31, 6:05 p.m.

As Sen. Judd Gregg (R-N.H.) emerges as President Barack Obama’s likely pick for Commerce secretary, Senate Republicans have begun to take stock of what Gregg’s departure from the chamber would mean to them.

Several news outlets were reporting on Saturday afternoon that Gregg is Obama’s top choice for the job and that the president could make the announcement within the next 24 hours.

Gregg’s departure could have implications far and wide, but the biggest impact could be felt in the Senate since his departure could give Democrats a 60-vote majority, courtesy of the Democratic New Hampshire governor, who has the ability to name Gregg’s replacement.

“It’s no secret we’re on bubble for a filibuster-proof Senate for Democrats, and that’s not a good thing,” National Republican Senatorial Committee Chairman John Cornyn (Texas) said in an interview Friday.

As the campaign committee chairman, Cornyn said the loss of Gregg “would make my new job harder when it comes to retaining that New Hampshire seat.”

Speculation on the Hill on Friday centered around what appeared to be an improbable theory that New Hampshire Gov. John Lynch (D), who is known for a strong independent streak, would appoint a Republican if Gregg exited. That appointee would fill out the remainder of Gregg’s current term, which expires in 2010.

“Perhaps if [Gregg] went into the administration, the Democratic Governor of New Hampshire would appoint a Republican Senator, so that wouldn’t change,” Senate Republican Conference Chairman Lamar Alexander (Tenn.) said. “I have no idea what the discussions are, and it’s really between Sen. Gregg and President Obama.”

But some Senate aides said the possibility of Lynch tapping a GOP caretaker for the seat could be a realistic scenario, given that few can envision a situation in which Gregg would take the Commerce gig without first ensuring his fellow Republicans continued to have at least the nominal ability to filibuster. Lynch may be persuaded to appoint a Republican in order to burnish his maverick credentials and avoid potential political backlash for giving Democrats an iron grip on the Senate, aides said.

Gregg did little Friday to dampen speculation or calm GOP fears about whether he would accept a nod from a Democratic president to head the Commerce Department. Gregg, the ranking member on the Budget Committee, would bring to the post ready-made experience and much-needed credibility with lawmakers on both sides of the aisle.

“I am aware that my name is one of those being considered by the White House for Secretary of Commerce, and am honored to be considered, along with others, for the position. Beyond that there is nothing more I can say at this time,” Gregg said in a statement.

Symantec Chief Executive Officer John Thompson also has been mentioned in media reports as a leading contender for the position. White House Press Secretary Robert Gibbs on Friday said no decision had been made on whom Obama would offer the spot to.

Still, GOP Senators indicated they were hoping Gregg would remain in the chamber but did not want to pressure him.

“When we were on floor voting last night, a number of us were standing there [with Gregg]. I didn’t ask him any point-blank questions,” Cornyn said. “Judd knows we’d like him to stay. I don’t think anyone felt the need for pleading.”

Alexander joked that he would mount a “friendly Republican filibuster” against the nomination should Gregg be picked.

“I told him he was going to have a hard time getting confirmed if he left,” he said.

Beyond the political ramifications, Republicans said, they would lose in Gregg a skilled tactician and thinker who is well-liked and respected by moderates and conservatives alike.

“Judd Gregg is one of our best Senators. He’s one of our best players,” Alexander said. “I’m not surprised President Obama is trying to recruit him. … He’s a very principled person, and he’ll make his own decision.”

Gregg enjoys a special relationship with Senate Minority Leader Mitch McConnell (R-Ky.), serving as part consigliere, part strategist and part henchman for the leader.

McConnell told Roll Call in 2007 that Gregg is “arguably our best sort of idea guy. I rely on him heavily. He’s a major player in the Senate whether he sits at the leadership table or not.”

Although rumored to have been a favored candidate to replace McConnell if the GOP leader had McConnell lost his re-election bid last fall, Gregg never expressed interest in running for the party hierarchy. But he does have a seat at the table as an unelected “counsel” to the leader. McConnell tapped Gregg as his lead negotiator on the $700 billion Wall Street bailout last October and has frequently let Gregg lead the party in floor fights with Democrats.

“I’m obviously concerned. Judd Gregg is one of our stars, and it would be a real loss for the Senate,” Cornyn said. “Having said that, it’s obviously a personal decision, and we’ll have to accept whatever that decision is.”

David M. Drucker contributed to this report.