Obama is just as determined to leave a mark by moving forward with regulation at a time when his legislative proposals appear dead on arrival at Capitol Hill.

Monday’s clash will also intensify a public relations and lobbying battle between green groups and business.

The Chamber of Commerce argues the rules could cost the U.S. economy $50 billion annually, while environmentalists see curbing power plant emissions as an historic moment in the climate change fight.

“When history is written [this rule] has the potential to be judged as the moment that the U.S. fully committed to fighting climate change,” said Michael Greenstone, an environmental economist at MIT.

Republicans are vowing to exhaust all avenues available to kill the regulation.