Much about the November midterms is uncertain, but there’s one thing prognosticators can assure: Speaker Nancy Pelosi will be less influential come Nov. 3.

The California Democrat would lose the gavel if Republicans sweep to power. But even if Democrats retain control, Republicans are all but certain to make significant gains. And Pelosi, who has been referred to as the most powerful Speaker in history, may soon be captaining a razor-thin majority and rethinking her approach to marshaling votes.

Although liberals would likely make up a greater percentage of a reduced House Democratic majority, moderate Members who survive the election probably will enjoy fresh influence because Pelosi no would longer be able to spare their votes. Pelosi has had the luxury over the past two years of letting a few moderates go their own way, but with her numbers slashed, she will have to negotiate more directly with the centrist bloc to get anything done. “It just takes a style of leadership that has not been hers so far,” said one Democratic strategist, who noted that Pelosi’s top-down leadership approach has relied largely on a structure of committees that, in many cases, are headed by close liberal allies. “That has to change.”

Democratic strategists say Pelosi, who became Speaker in 2007, would need to build stronger ties to members of the moderate Blue Dog and New Democrat coalitions, perhaps bringing those groups to the negotiating table earlier on in the legislative process.

The current 39-seat Democratic edge has afforded the California Democrat enough of a cushion to pass controversial initiatives such as the climate change, health care and financial regulatory reform bills with little or no GOP support. She could even afford Democratic defections: 44 Democrats voted against the final version of health care reform in March, while 44 Democrats voted against the climate change bill in June 2009.

“That’s a luxury of Members in tough districts not having to vote with us,” said Steve Elmendorf, a lobbyist who served as chief of staff to then-Minority Leader Dick Gephardt (D-Mo.). “You won’t have that luxury.”

Even with votes to spare, Pelosi has struggled to build consensus within her diverse Caucus. In recent months, for example, Blue Dog Coalition opposition nearly scuttled her plans to bring campaign finance reform and jobs legislation to the floor.

Still, Pelosi spokesman Nadeam Elshami downplayed the suggestion that the Speaker would have to change tactics in a smaller majority.

“We will continue to operate the same way we’ve always operated, which is through consensus in our Caucus,” he said. “We build consensus in our Caucus, and that’s the strength of the Democratic Caucus on whatever the issue is. And that will continue to be the case.”

Pelosi allies point out that she already meets weekly with freshman and sophomore Democrats, many of whom hail from GOP-leaning districts and are Blue Dogs or New Democrats. They also point out that Pelosi often schedules meetings with different factions of her Caucus when Members have concerns about specific bills.

Although Majority Leader Steny Hoyer (D-Md.) has closer ties to moderates, Pelosi met numerous times with reticent Blue Dogs to persuade them to support the health care bill and with New Democrats to try to allay concerns about the financial reform measure.

Still, some Democrats say privately that midterm elections could fuel a rift that has developed between Pelosi and some moderates who have complained that she and President Barack Obama have pushed too hard and too fast for legislative items that do not play well in their districts.

Assuming a brutal Nov. 2, one senior Democratic aide predicted that “Members will be very wary of anything coming from leadership or the White House — any agenda or anything controversial or big” and that moderate Democrats could feel less inclined to toe the party line and do what leadership asks.

“Members who come back will probably feel they came back largely through their own efforts,” the aide said.

Pelosi didn’t do much outreach to moderate Democrats in August, said several Democrats on K Street with ties to Blue Dogs. Those lobbyists said many moderates think Pelosi doesn’t appreciate the fact that they took tough votes for her over the past two years and now may lose re-election as a result. Those Members, like all Democrats, would be expected to vote for Pelosi for Speaker in the next Congress.

“The moderates that are left and those in tough races are going to be much more attuned to their districts,” one Democratic lobbyist said. “Getting them to take some of the votes she’s been able to get in the last couple of years is going to be much harder.”

Still, a handful of Democrats say that if they defy the odds and keep the House, Pelosi’s stock could rise.

“They will certainly have beaten expectations and surprised the political world,” a former House Democratic leadership aide said. “So I think she’ll be in a very strong position.”

The former aide noted that as long as Pelosi is Speaker, she would have many carrots — such as committee assignments and overseas travel — at her disposal to woo moderates. The aide pointed out that unlike the Senate, where 60 votes are needed to pass most agenda items, the House is a true majority-run institution.

“Whether you have a majority of one or a majority of 50, you can still run the floor and run the institution,” the former aide said. “Having even a one-vote majority is significant.”

A narrow majority would provide Pelosi with new incentive to hunt across the aisle for votes. But to lure moderate Republicans, Pelosi would have to “overhaul her operating style” and make a show of goodwill by working to pass a broadly bipartisan bill early in the session, said Ron Bonjean, a former aide to Speaker Dennis Hastert (R-Ill.).

“Speaker Pelosi is viewed as very partisan and very unwilling to make deals for the sake of getting something done,” Bonjean said, adding that Pelosi would have to battle a widespread Republican perception that “she would rather have her way than get something out of the Congress.”

And Republican leaders, who have shown little interest in cooperating with Democrats this Congress, also would be unlikely to change that tack if they fall short of winning control of the chamber.

Presidential politics could further complicate matters for Pelosi in the 112th Congress. Since Obama took office in 2009, Pelosi has been able to partner with the White House to pass major pieces of the party’s agenda. But as Obama eyes re-election in 2012, many Democrats predict that relationship will cool, suggesting that the White House will shift to the center and steer clear of the wants of liberals who make up Pelosi’s base of support.

“Regardless of who controls the House, you are going to see a movement to the center,” said former Rep. Charlie Stenholm (D-Texas), who was a founding member of the Blue Dog Coalition. The Democratic House leadership “will not be able to push as strong a progressive policy as they’ve tried to push. … The [Blue Dogs] that return will have been vindicated by their constituency.”

But Stenholm predicted that as a whole, a leaner Democratic Caucus would “be more amenable to more centrist positions,” even if it is more highly concentrated with liberals.

Bonjean floated a different theory, predicting that Pelosi might face increased push-back from liberals if she makes too much of an attempt to accommodate Republicans or moderate Democrats.

“Because a lot of them are going to be liberals left, they’re going to be very frustrated if Speaker Pelosi tries to create bipartisan deals to get things through,” he said. “Now you’re going to have liberals very concerned about having to take bipartisan votes that won’t play well in their districts.”