The last GOP nominee had not yet conceded Wednesday and Senate Republicans had already started searching for a leader to find a path back to 51 seats.

Two lawmakers expressed immediate interest in the National Republican Senatorial Committee chairman post for the 2014 cycle: Sen. Rob Portman (Ohio), a Conference favorite, and Sen. Jerry Moran (Kan.), who has burned up the phone lines for months seeking the position.

The job of Senate campaign committee chief can be thankless at times, but it can also pay big dividends. Just ask Democratic Senatorial Campaign Committee Chairwoman Patty Murray (Wash.), who delivered a huge victory for her caucus Tuesday.

But both committees face unprecedented challenges next cycle.

For the second cycle in a row, Democrats must guard almost twice as many seats as Republicans — many in GOP strongholds such as Alaska and Louisiana. Senate Republicans, meanwhile, failed to meet expectations at the ballot box for the second cycle.

The GOP hoped to win the majority this cycle, but instead ceded two seats to Democrats. Part of the problem lies with the party’s brutal primaries, which have resulted in lackluster candidates being nominated and cost the party at least five seats during the past two cycles.

“The challenge for the next chair will be how to mitigate this,” a Senate GOP aide said. “How early should the NRSC play in a race and prop up a more electable candidate, or will they let primaries take their course and hope that candidate can appeal to the masses?”

Portman’s interest came as welcome news to much of the Senate GOP, which views him as a strong fundraiser, magnanimous colleague and a keen political mind. He raised more money for the NRSC than any other freshman this cycle, and he maintains a deep donor base in the posh parts of southern Ohio, a battleground state he won by nearly 19 points last cycle.

“It’s important to have someone in that position who understands the fundamentals, but who can also provide some leadership and vision to the committee,” said Bob Paduchik, a former top political aide for Portman. “With Rob, he’s the best package for both.”

Weeks before the polls closed Tuesday, Senate Republicans started pleading with Portman to consider the gig. A Republican close to Portman confirmed he’s thinking about it.

Moran started lobbying his colleagues one-by-one for their support months ago. He’s openly pursued the post, and has already called to congratulate the new GOP Senate class.

“I have a sufficient number of commitments that if the election is held, I would be successful in becoming the chair,” Moran told Roll Call on Wednesday.

But much of that was before Portman’s allies told reporters that he’s thinking about the gig. Moran’s boosters said his tea party appeal will help block primary challenges for potentially vulnerable Members such as Sens. Pat Roberts (Kan.), Lamar Alexander (Tenn.) and Lindsey Graham (S.C.).

Still, Portman’s fundraising prowess make him the clear front-runner — if he wants the job. Other contenders, such as Sens. Kelly Ayotte (N.H.), Roy Blunt (Mo.) and Marco Rubio (Fla.) indicated through aides that they’re not interested.

Senate Republicans plan to hold the NRSC election on Wednesday, according to a top aide.

Senate Democrats could take much longer to find a new head for their campaign arm.

Senate Majority Leader Harry Reid (D-Nev.) has not yet set a timetable to appoint a new DSCC chairman, according to his spokesman, Adam Jentleson. It took Reid several weeks (and a few rejected offers) before he convinced Murray to take the post last cycle.

Murray declined to say whether she is interested in running the DSCC for a second cycle in a row. She ran the committee in 2002 as well.

“I don’t know who will chair the DSCC in the next cycle,” Murray told reporters on a conference call.

If she doesn’t want another turn at the helm, Democratic aides immediately mentioned Sen. Michael Bennet (Colo.) as a contender. Bennet rebuffed Reid’s request to run the committee two years ago. But Bennet’s top aide, Guy Cecil, served as the DSCC’s executive director this cycle.

“The only conversations Sen. Bennet has had about the DSCC are about how proud he is of Guy Cecil for his excellent work this cycle actually picking up seats,” Bennet spokesman Adam Bozzi said.

Democrats praise Bennet’s comfort among the “Acela Corridor” crowd, as well as his ability to raise money in the Midwest and west and “not be completely out of his element.”

Otherwise, speculation about who might be tapped centered around Sens. Kirsten Gillibrand (N.Y.), Amy Klobuchar (Minn.) and Sheldon Whitehouse (R.I.) — all of whom just won re-election. A Klobuchar spokeswoman declined to comment, while Gillibrand and Whitehouse aides did not return requests for comment.

Gillibrand proved herself as a strong fundraiser who has already started to build a national donor network. But Democrats caution that she’s sought re-election for two cycles in a row since she was appointed to the Senate in early 2008. They emphasized that she might prefer a break from the fundraising circuit.

Klobuchar won re-election handily in a competitive state and boasts a donor base among the corporate community around the wealthy Twin Cities suburbs. But she’s also been mentioned as a potential appointment in a second Obama administration, perhaps as attorney general or even on the Supreme Court.

Whitehouse is also comfortable with business leaders and is viewed as a pragmatic Democrat. He was offered the job this cycle and turned it down because of his re-election bid.

Some Democrats argue that the next chairman has to be someone Senators would welcome a visit from in their home state, no matter how conservative the electorate is.

“It’s got to be someone from the moderate wing of the party,” said one former Senate Democratic aide, who argued for a “friendly face for business” to fundraise.