With Members anxious to leave town by the end of September, Senate Republicans acknowledged Wednesday they face a difficult dilemma: how to let endangered incumbents go home to campaign while holding firm against the Democratic energy and spending agendas.

“That’s obviously a calculation our leaders will have to make, and they’ll probably get a lot of input from our Members who are up about their desire to get back home,” Senate Chief Deputy Minority Whip John Thune (R-S.D.) said. “At the same time, whatever happens here between now and the end of the month, we’re not giving away the farm in terms of the things that we want to accomplish.”

Republicans have 23 seats to defend, and many polls show Democrats poised to capture four or more of those. But major issues involving energy policy, economic stimulus and government spending — all potential lightning rods — are on tap in the chamber for the next two and a half weeks.

Even Senate Minority Leader Mitch McConnell (R-Ky.) privately told Republicans during their weekly lunch Tuesday that he hopes agreements could be reached with Democrats to ensure the Senate adjourns Sept. 26 as planned. One GOP aide familiar with McConnell’s lunchtime presentation acknowledged that not only is it in the best interest of incumbent lawmakers for the Senate to shutter its doors as soon as possible, but it could also aid Republican presidential nominee Sen. John McCain (Ariz.).

McConnell, who also faces a spirited challenge this year, told his colleagues Tuesday that “the best thing we can do for [McCain] is to get out of town,” the aide said, noting that presidential nominees from both parties often urge Congressional leaders to avoid distracting voters.

Achieving that goal, however, could complicate Republican threats to hold up both next week’s energy debate and a continuing resolution intended to keep the government funded until individual spending bills can be passed.

Republicans have said they may not agree to debate those issues if they are not provided an opportunity to vote on offshore oil drilling or if Democrats insert additional spending into the CR.

However, Republicans could start losing key Members if they push those fights too long. Sen. Norm Coleman, who is among the most endangered of GOP incumbents this year, said he’ll be campaigning in Minnesota by the end of the month.

“I’m going home,” Coleman said. “I think the Democrats are going to suffer from not getting things done and they’ll pay a price for that. I’m not going stay in Washington and play these games.”

Coleman may not have to make good on that threat, given that GOP Senators say they are encouraged by the olive branches already being offered to them by Democrats on energy.

“If the approach is cooperation, then I think we’re certainly willing to cooperate,” Sen. Judd Gregg (R-N.H.) said. “I believe the energy bill can be structured in a way that’s cooperative, where we get votes and everybody gets their major vote. … Then the CR hopefully doesn’t get loaded up. If it doesn’t get loaded up, I certainly would think there’d be a lot of cooperation.”

Gregg said the current state of leadership talks on energy legislation gave him reason for optimism.

“I believe that there is significant sentiment on both sides of the aisle to get out of here,” Gregg said. “We know what we need to do, and it appears there’s a path to do it.”

As for the expected showdown over the CR’s likely inclusion of a long-standing moratorium on offshore oil drilling, both Gregg and Thune said that issue could lose steam if during next week’s energy debate, Republicans get the votes they want on expanding drilling leases on the Outer Continental Shelf.

Blocking passage of the CR would result in a government shutdown, Democrats warn.

Democrats said they hope the chamber can finish its business by Sept. 26, but they noted they don’t have the same considerations that Republicans have.

“I want to leave, but I’m not going to be pushed into leaving,” Senate Majority Leader Harry Reid (D-Nev.) warned. “We have all of our incumbents who are going to win. We don’t have a single Democratic Senator who’s in any trouble electorally.”

Democratic Senatorial Campaign Committee Chairman Charles Schumer (N.Y.) echoed that sentiment. “If you’re up for reelection, you want to be home, and they have more people in trouble than us. So there’d be an imperative for them to not hold us on the political side,” Schumer said. “But on the substantive side, I don’t know where they come down.”

Republicans, however, cautioned that Democrats have an incentive to smooth the endgame as well.

“The risk this year, because it’s a presidential year, may cut both ways,” Thune said. “If they’re trying to pick fights before Congress leaves town, I don’t think that’s probably to their advantage either … having that kind of splash back on” Democratic presidential nominee Sen. Barack Obama (Ill.).

Indeed, the Democrats’ willingness to allow votes on a number of pro-drilling amendments next week appears to be geared toward ensuring they can get out of town by their self-imposed deadline.

However, Democrats said the GOP split between forcing their point of view on energy and going home to campaign will ultimately play more to the Democrats’ advantage.

“There are two groups of Republicans right now,” one senior Senate Democratic aide said, “those with a shutdown-the-government mentality, and those who are fighting for their political lives in this year’s election.”

John Stanton contributed to this report.