The Clean Power Plan is intended to be a key part of the president's legacy on global warming, which he pledged to fight as a candidate for the White House in 2008.

The effort also sets up climate change as a political lightning rod in the 2016 presidential election.

Former Secretary of State Hillary Clinton, the front-runner for the Democratic nomination, said she would defend the plan while Jeb Bush, one of a slew of Republicans running for their party's nomination, said it would cost people jobs.

"EXPENSIVE, ARROGANT"

Other leading Republicans also stressed what they said were the costs to the economy from the plan.

Senate Majority Leader Mitch McConnell said the new rules would shutter power plants and drive up electricity costs.

"I will do everything I can to stop it," he said.

The Republican Speaker of the House of Representatives, John Boehner, called the plan an "energy tax."

"I believe this final plan is an expensive, arrogant insult to Americans who are struggling to make ends meet," he said.

Obama rejected criticism that his plan would increase energy bills for Americans and hurt the poor, saying, "If you care about low-income, minority communities, start protecting the air that they breathe."

The re-vamped Clean Power Plan gave a boost to renewable energy, which would account for 28 percent of the US energy mix by 2030 from just under 10 percent currently if enacted.

Jeff Holmstead, a partner at Bracewell & Giuliani and a former official at the Environmental Protection Agency, said the bigger role for clean energy such a solar and wind was meant to impress allies in the Paris talks.

"The EPA did a little bit of puffery to make the US commitment look even bolder before Paris and they (allies) should be wary of the US plan," he said. "Europeans especially know too well that overreliance on intermittent energy sources can create its own economic hardships."