Key Senate Democrats, believing the politics have shifted in their favor, are renewing their effort to require electric utilities to produce more power from renewable sources such as wind and solar.

Such measures have passed the Senate three times in years past but died in a GOP-controlled House. Now that the Democrats are running the House, and fears about dependence on foreign oil and global warming are foremost in many minds, Senate leaders like Energy Chairman Jeff Bingaman, D-N.M., think the timing might finally be right.

Supporters say a national “renewable portfolio standard” requiring 10 percent to 20 percent of electricity to be produced from renewables could go far toward lessening U.S. fossil fuel dependence. Less than 5 percent of the nation’s electricity now comes from renewable sources other than hydroelectricity. Twenty-two states have enacted renewable standards.

On Thursday, a diverse group of 186 signatories — including some of the biggest names in industry, manufacturing and electric utilities, along with environmental groups — sent a letter to congressional leaders urging passage of a national renewable portfolio standard.

“It’s the broadest ever, it’s the biggest ever” range of support seen for pushing the renewable standard, said Bingaman spokesman Bill Wicker of the spectrum of signatories, which includes General Electric, BP America, Google and the Edison Electric Electric Institute, which represents investor-owned utilities.

Wicker called the effort “a very powerful endorsement” that could go far toward persuading lawmakers to support a renewable electricity standard.

But there will be at least one big hurdle: While many House Democrats, including Energy Committee Chairman John D. Dingell of Michigan, are on record supporting a renewable standard, one key player strongly opposes it.

Democrat Rick Boucher, who hails from coal-rich southwest Virginia, has consistently opposed a renewable electricity standard. Boucher also heads the House Energy subcommittee charged with crafting energy and climate change legislation, and he says that right now he has no intention of including a renewable portfolio standard in an energy bill his panel is preparing for the floor by early July.

Boucher traditionally has fought any measure that could threaten his district’s coal industry or raise electricity prices. This fall, Boucher plans to introduce legislation aimed at curbing global warming with a mandate to cut carbon emissions — a tough pill to swallow for any industry. That bill will take top priority, and adding the pressure of renewable energy sourcing on top of it could be too much for the utilities and ratepayers to take, Boucher says.

“The counter-argument is that, at a time when we’re planning to have a mandatory control program for greenhouse gases, there is little reason to also have a requirement that a certain percentage of fuels for electricity generation come from renewable sources,” Boucher said.

He acknowledged that a colleague could very well propose a renewable standard provision during the crafting of the upcoming energy and climate change bills, and anticipates “a spirited argument” if it does come up.

Boucher added that his new role as subcommittee chairman requires him to consider policy advantages beyond the reaches of his district — so he shied away from an absolute “no” to the proposal.

“Historically I have opposed the RPS provision. I think the arguments against it are strong. But I am for the moment going to withhold judgment,” Boucher said.

And of course, if such a provision is not part of the energy package his committee assembles, it could be added later as an amendment during debate on the House floor.

Then control of the issue would be in the hands of House Speaker Nancy Pelosi, D-Calif., who “believes that we need to increase the amount of electricity that comes from renewables in the United States above where we are today,” according to a Pelosi aide.

In an e-mail, the aide wrote that Pelosi “supports incorporating more renewables into our nation’s energy mix, whether it is through use in fuels for our cars or electricity for our homes and businesses.”

Bingaman wants his renewables proposal to be passed as an amendment to a major Senate energy package (S 1419). When debate begins on that measure in early June, Bingaman will have at the ready an amendment to require major utilities to generate 15 percent of their electricity from renewable sources by 2020.

Bingaman’s staff say they anticipate bipartisan passage of the proposal. Fifty senators, including Democratic leaders and four Republicans, have signed a letter calling for a strong renewable portfolio standard.

Wicker said Bingaman’s staff feels “optimistic” about the proposal’s chances on the House floor if it passes the Senate, despite the potential opposition from Boucher.

“As it’s never had a full airing on the House side, we’re confident as more members learn about the benefits, support will continue to build, and they’ll vote for passage,” Wicker said.

That’s also where supporters of the measure think lobbying from interest groups will come in.

The director of the Blue Green Alliance, an initiative of the United Steel Workers and the Sierra Club, said its members view the renewable portfolio standard as a way to boost jobs and help the environment.

“Up and down the line we can see that embracing the clean energy economy is going to be the growth engine of jobs of the future, particularly in the Midwestern industrial economy,” said alliance director David Foster.

Advocates working the House for support say they feel optimistic because so many states already have passed similar standards.

“Often these things start with the states and build up and come to a head. My expectations are very high that this will be the year Congress passes RPS, with the confluence of so many groups and states supporting it,” Foster said.

Anna Aurelio of the U.S. Public Interest Research Group added, “More than 219 House members come from states with RPS standards, so we think we could get some real excitement from the House.”

But even if those groups secure House passage, a final battle looms with the White House, which historically has opposed a national renewable electricity standard — though it has never gone so far as to threaten a veto, Wicker said. The White House contends that no national standard is needed, and that states can create their own renewable regulations.

On Wednesday, an Energy Department spokeswoman, Julie Ruggiero, wrote in an e-mail, “Traditionally, we have opposed a national renewable portfolio standard due to the fact that each state has very different renewable resources and can utilize renewable energy in different ways. A one-size-fits-all approach will not allow us to best maximize each state’s resources.”

But Senate Democrats and their allies are betting that a national standard might even make it past President Bush, especially if it ultimately comes couched in a major piece of energy legislation with bipartisan blessing.

“He might not risk killing a whole energy package over just one provision,” Wicker said.