President Barack Obama on Tuesday pledged that he would not back down on efforts to boost clean energy, warning that the United States risked being left behind by China and Germany.

But in a nod to political realities, Obama acknowledged in his annual State of the Union address that the deeply divided Congress would not approve comprehensive legislation to fight climate change.

Obama cast himself as a supporter of all forms of energy. He vowed "every possible action" to develop natural gas and pledged support for "fracking," the controversial technology that extracts gas from rock deep under the soil.

"This country needs an all-out, all-of-the-above strategy that develops every available source of American energy -- a strategy that's cleaner, cheaper and full of new jobs," Obama said, bringing a sustained ovation from lawmakers in the joint session of Congress.

But Obama challenged Congress to support him on developing clean energy, demonstrating his point by bringing to the chamber a laid-off worker who found new work with Michigan-based wind turbine manufacturer Energetx.

"The differences in this chamber may be too deep right now to pass a comprehensive plan to fight climate change. But there's no reason why Congress shouldn't at least set a clean energy standard that creates a market for innovation," Obama said.

"I will not cede the wind or solar or battery industry to China or Germany because we refuse to make the same commitment here. We have subsidized oil companies for a century. That's long enough," Obama said.

Specifically, Obama urged Congress to renew tax credits for clean energy, with incentives for wind power set to expire at the end of 2012. He also renewed calls to end subsidies to oil companies, saying they were already profitable.

Obama also set a goal of powering three million homes through renewable energy on public lands, the latest effort by his administration to expand areas of potential use for solar, wind and green technologies.

The rival Republican Party has hammered Obama over a $535 million government loan for Solyndra, a solar firm that went bankrupt, and his administration's rejection of the controversial Keystone XL pipeline project from Canada.

The Republicans, oil industry and Canadian government say that the Keystone project would boost the economy and provide reliable energy from an ally. A US State Department analysis said the pipeline would create 5,000 to 6,000 jobs in construction for two years.

But environmentalists led a protest campaign to press Obama to reject the pipeline as it would go through sensitive lands in Nebraska and bring oil from tar sands, causing much higher emissions of carbon blamed for global warming.

"The extremism that stifles the development of homegrown energy, or cancels a perfectly safe pipeline that would employ tens of thousands, or jacks up consumer utility bills for no improvement in either human health or world temperature, is a pro-poverty policy," said Indiana Governor Mitch Daniels, who delivered the Republican response to Obama's address.

House Speaker John Boehner, referring to Canadian threats to sell oil to China, said that Obama was "shipping American energy security to the Chinese" and "selling out American jobs for politics."

Obama did not refer directly to Republican criticisms but, in a likely allusion to Solyndra, he said: "Some technologies don't pan out; some companies fail."

Legislation backed by Obama to fight climate change died in the US Senate in 2010 amid staunch opposition from Republicans, many of whom question scientists' view that carbon emissions are behind rising temperatures.