(Bloomberg News) President Barack Obama pushed drilling for gas in shale rock and support for cleaner energy sources to boost the economy in his final State of the Union address before facing U.S. voters in November.

Hydraulic fracturing, the process of injecting water, sand and chemicals underground to free gas trapped in rock, could create more than 600,000 jobs by the end of the decade, Obama said yesterday. The process, called fracking, is among a list of energy policies Obama said would fuel economic growth.

"We have a supply of natural gas that can last America nearly 100 years, and my administration will take every possible action to safely develop this energy," Obama said.

Obama reiterated support for conservation and cleaner sources of power and pledged more oil drilling as part of an 'all-out, all-of-the-above'' policy "that's cleaner, cheaper, and full of new jobs." He said domestic energy production is at an eight-year high and imports of foreign oil were declining, prompting criticism from Republicans.

"It's just a blind accident, if in fact we are producing more oil or natural gas than in previous years, because it's not because of any of his efforts," Representative Darrell Issa, a California Republican and head of the House Oversight and Government Reform Committee, said after the speech.

Republicans also sought to contrast Obama's pledge to use energy policy to create jobs with his denial of a permit to TransCanada Corp.'s Keystone XL pipeline to connect Canada's oil sands to refineries on the Gulf coast.

Republicans, Keystone

Indiana Governor Mitch Daniels, delivering the Republican response to a nationwide television audience, called Keystone a "perfectly safe pipeline that would employ tens of thousands" and said that Obama has sought to stifle energy production in the U.S.

Keystone would "have done more than any other project to increase our energy security and revive our economy," Senator James Inhofe, an Oklahoma Republican, said in a statement after the speech.

Obama announced incentives to make industries more energy efficient, and again urged Congress to require that a larger percentage of the nation's power come from low-pollution sources.