WASHINGTON — Facing a Congress that is more hostile to environmental regulation, President Barack Obama is moderating his environmental goals: a clean energy standard that mixes nuclear, natural gas and "clean coal" with wind, solar and other renewable sources.

In his State of the Union address Tuesday night, Obama called for 80 per cent of the nation's electricity to come from clean sources by 2035. That goal represents a new strategy to reduce emissions of carbon dioxide blamed for global warming, following the death of cap-and-trade legislation that Obama pushed in Congress for the last two years.

The new target would double the percentage of electricity that comes from clean energy sources, according to a White House fact sheet. Clean coal, which would be produced by an experimental technology not yet available commercially, and "efficient natural gas" would be given only partial credits toward the goal.

The clean energy standard represents a second fallback position to cap and trade. Under the cap-and-trade system, government places a limit on pollution and allows companies to buy and sell pollution permits under that ceiling. Companies that can reduce their emissions cheaply can then sell their unused credits to those that cannot afford the costs of emission controls.

Last year, a powerful coalition of renewable energy producers, environmental groups, governors and even some utilities couldn't push a renewable electricity standard of 15 per cent across the finish line, in part because of regional resistance. In the Southeast, for example, it was argued that the region lacks renewable sources like abundant levels of wind.

The nuclear industry soon touted the idea of a broader clean energy standard, which got a nod from Energy Secretary Steven Chu last month. Chu said a goal of 50 per cent by 2050 would be "about right" -- but it turned out to be much less than Obama is proposing. The energy secretary told reporters Wednesday that he had been responding to a suggested level.

"Now, since that time, we have gone back and looked at it and it depends on how you define it," Chu said after an online clean energy town hall. The U.S., he said, already gets about 40 per cent of its electricity from clean energy sources and more than 30 percent from carbon-free sources.

Chu called the new proposal "a recognition that solutions can be different in different parts of the United States, but ... this is the goal we're looking for and depending on the region, you have different options of getting to that eventual goal."

Whether the administration can win over many Republicans isn't clear yet. Rep. Doc Hastings, a Washington Republican who chairs the House Natural Resources Committee, said Obama "needs to embrace a robust plan to produce all types of American energy -- from renewable to American-made oil and natural gas -- and it has to be done without harmful government subsidies or unrealistic mandates."

Sen. Lamar Alexander, R-Tenn., a big proponent of nuclear power, said the policy was an improvement over a renewable energy standard, which he dismissed as "just a national windmill policy." But he said he didn't support a clean energy standard either.

At the other end of the political spectrum, several environmental groups were opposed to elements of the broader mandate.

"Developing clean energy sources for more of our electricity is another way to skin the carbon cat," said Bob Deans, a spokesman for the Natural Resources Defense Council. "It's important, though, that we do the job right, not simply redefine the cat."

Deans called clean coal an oxymoron and said the government should not be subsidizing nuclear power because of concerns over waste and nuclear proliferation.

"Coal, nuclear power, biofuels and natural gas are inherently dirty," said Erich Pica, president of Friends of the Earth. "Telling Americans anything else is just misleading."

But Obama received some support from key Democratic lawmakers.

"This year we need to double down instead of walking away," said Sen. John Kerry, D-Mass., one of the leaders of the climate legislation effort last year. "Today's energy economy is a US$6 trillion market, and the fastest-growing segment is clean energy."

Sen. Mark Udall, D-Colo., a longtime supporter of a renewable energy standard, said that the country needs an "all-of-the-above approach," including natural gas and nuclear.

"I was encouraged to hear President Obama agrees with me," said Udall, D-Colo.