Negotiations on a major energy bill begin Monday — but Democratic leaders have already drawn fire for taking the three biggest and most contentious issues off the table.

The three issues those leaders cite as their top priorities in crafting new energy policy — raising vehicle fuel economy standards and setting nationwide mandates for renewable fuels and electricity — will not be up for discussion as Energy Committee staffers from both chambers and parties convene to start hammering out a compromise bill.

Instead, those highly controversial provisions — which, if enacted, would signal a new direction in U.S. energy policy — will be worked out behind closed doors between House Speaker Nancy Pelosi, D-Calif., and Senate Majority Leader Harry Reid, D-Nev., say congressional aides.

Whatever bill emerges from the staff and leadership talks will then have to be sent back to both chambers for passage.

Each of those initiatives passed one chamber, but not the other, this summer as part of a larger energy bill. The Senate passed a measure (HR 6) that would significantly raise fuel economy standards for cars and light trucks and would mandate production of 36 billion gallons of biofuels by 2022. The House bill (HR 3221) would require 15 percent of the nation’s electricity to come from renewable sources by 2020.

But lawmakers question whether one bill containing all three contentious measures could make it through both chambers this year, especially as the fuel economy and renewable electricity provisions have divided Democrats, making a majority uncertain. Analysts say that appears to be the reason congressional leaders are keeping those pieces off the negotiating table, and trying to engineer the bill themselves — a strategy that has drawn plenty of criticism from Republicans.

“I think the notion of establishing a negotiation framework where the three biggest elements of the plan are off the table is a fraud,” said Chris Tucker, communications director for House Republican Whip Roy Blunt, R-Mo.

Many Republicans may not even attend the initial negotiations, in order to protest their inability to weigh in on the three key pieces. “At this time it’s unclear if Republicans are going to be attending talks on Monday,” said Matt LeTourneau, a spokesman for Senate Energy Committee Republicans. “One of our sticking points is that certain items are off the table. The issues that took up so much time on the Senate floor and House floor are not open for discussion.”

Charges of partisan perfidy in energy negotiations are not new: In 2003, the Republican chairmen of the Senate and House energy committees, Sen. Pete V. Domenici of New Mexico and Rep. W.J. “Billy” Tauzin of Louisiana, privately drafted a proposal for consideration by conferees on a major energy bill — a process one Democratic aide called “the illusion of inclusion.” The plan eventually won conference approval amid partisan bickering, but the bill ultimately failed.

While key issues may be off staffers’ negotiating table, that doesn’t appear to have deterred a major lobbying push on at least one of them: raising corporate average fuel economy, or CAFE, standards.

Efforts to legislate better vehicle mileage have been stalled for more than 20 years, but this summer’s Senate energy package included a provision that would require manufacturers to raise vehicle fleet averages to at least 35 miles per gallon by 2020 for cars, light trucks and sport utility vehicles.

Pelosi has said she strongly supports incorporating that provision in the final energy deal, but it has met with powerful pushback from a broad group of opponents, including The Alliance of Automobile Manufacturers and the influential Blue Dog Coalition, a group of fiscally conservative House Democrats. In the past, these groups have pushed against moves to raise CAFE standards entirely — but now they are pushing instead for a more modest House bill (HR 2927) by Reps. Baron P. Hill, D-Ind., and Lee Terry, R-Neb. Their bill would leave separate regulations in place for cars and “light trucks,” such as sport utility vehicles, while setting the overall fuel economy at 32 miles per gallon to 35 mpg by 2022.

That has brought along the support of groups that have previously opposed all efforts to tighten fuel economy standards, but who now say they would support a raise with separate standards for cars and light trucks. The push includes influential groups that depend on light trucks to do business, including the American Farm Bureau Federation; the American Recreation Coalition; Associated General Contractors; International Professional Rodeo Association; National Association of Plumbing, Heating and Cooling Contractors; and the Small Business and Entrepreneurship Council. Another key supporter of the Hill-Terry bill is powerful House Energy Chairman John D. Dingell, D-Mich., who has long been a key opponent of any raise in fuel economy standards, but has cosponsored the Hill-Terry measure.

Counter-lobbying by environmental groups is also in full force. “What this effort really boils down to is nothing more than an 11th-hour attempt by a boatload of lobbyists to scuttle a boosted fuel-economy standard that the Senate already passed,” said Deron Lovaas, a vehicles expert at the Natural Resources Defense Council.

But staffers say the Democratic leadership’s “off-the-table” strategy will likely keep that proposal out of discussions and the final product. “The chances for Hill-Terry getting into the mix are very slim,” said a Democratic leadership aide.