Barack Obama's resort to executive action to impose tough new rules to further clean the nation's air have ignited raging partisan fires on Capitol Hill.
Like the U.S. President's equally incendiary decision to permit nearly five million undocumented immigrants to stay free of the fear of deportation, the executive order on controversial Environmental Protection Agency (EPA) rules will frame Mr. Obama's legacy and may shape the battleground to succeed him in 2016. The proposed EPA rules could take months, or longer.
The brief post-midterm truce – during which both victorious Republicans and a not-so-chastened President vowed to seek common ground – lasted barely a few hours and apparently was mainly for show.
Now, a full-fledged political battle is under way over Mr. Obama's attempt to govern with or without Congress. The fight will only intensify in January when Republicans take control of both Houses of Congress with a solid majority in the Senate.
"I fully intend to do everything I can do to fight these onerous EPA regulations," warned Senator Mitch McConnell, the incoming majority leader. Republicans vow to strangle the EPA by throttling its funding.
Mr. Obama's most vociferous opponents claim the former constitutional law professor is trampling on the nation's founding principles, behaving like an emperor not an elected president in a system of carefully constructed checks and balances with powers deliberately divided.
"It is lawless. It is unconstitutional. He is defiant and angry at the American people. If he acts by executive diktat, President Obama will not be acting as a president, he will be acting as a monarch," says Senator Ted Cruz, a Texas Republican and likely presidential contender in 2016.
Mr. Obama seems nonplussed by such accusations.
"We've heard rhetoric for some time. Their most recent statement referred to 'Emperor Obama,'" said his spokesman Josh Earnest. "The fact is, the President is somebody who is willing to examine the law, review the law and use every element of that law to make progress for the American people and that's a criticism the President wears with badge of honour."
Long before the Democratic Party's crushing defeat in last month's elections, Mr. Obama had signalled he was ready to rule with or without Congress.
"When I can act on my own without Congress, I'm going to do so," he said, nearly a year ago in his State of the Union address.
The President's defenders claim he has been forced to govern by fiat because partisan gridlock has stalemated Congress. They blame Republicans, calling them the "Party of No."
But Mr. Obama's critics say the one-term senator who had no experience running anything before he was elected president has shown a chronic unwillingness to compromise, to engage, to forge the sort of deals made by his predecessors including Bill Clinton and Ronald Reagan.
The looming battle over tougher EPA smog standards is as much about what Mr. Obama is doing as well as how he is doing it.
The new rules will cost $3.4-trillion (U.S.) in lost economic output and destroy nearly three million jobs over the next 25 years, claims the National Association of Manufacturers. It said the proposed EPA regulation "threatens to be the most expensive ever."
Similarly, dire warnings have greeted every EPA standard since former-president Richard Nixon created the agency 44 years ago.
Mr. McConnell calls it all part of Mr. Obama's "war on coal."
The battle won't be waged just on Capitol Hill. For the third time in less than two years, the Supreme Court will take a case that examines just how far a president can order the EPA to go. Last June, the court said the President had overreached, although the wording was kinder. "An agency has no power to 'tailor' legislation to bureaucratic policy goals by rewriting unambiguous statutory terms," the Supreme Court ruled.