The king of coal has gone from condemning the last president of the United States to praising the sitting occupant of the White House.

"President Donald Trump was very courageous and very prudent to withdraw the United States from the Paris climate accord," Murray Energy CEO Robert Murray told CNNMoney this week.

The boss of the largest private U.S. coal miner said it's "wonderful" Trump followed through on his campaign promise to ditch the Paris climate accord.

Trump painted the global climate deal as deeply unfair to America's beaten-down coal country, which he's vowed to revive through deregulation.

Murray remains deeply critical of President Obama, calling him the "greatest destroyer the United States has ever had." The coal exec blamed Obama's environmental regulations for "causing pain and harm" to 63,000 coal mining families whose jobs were lost.

Not surprisingly, Murray believes the threat of climate change is exaggerated and that the Paris deal would have done little to help the environment.

"We don't have a global warming problem in this world. It's fraudulent in how it's been presented. It's alarmist. The real problem is energy poverty," Murray said, referring to countries like India, that need more electricity.

Of course, many business leaders disagree with that sentiment, as evidenced by the stream of prominent CEOs who criticized Trump's Paris decision. Even oil giant ExxonMobil (XOM) urged Trump to stay in the Paris accord, praising the agreement as an "effective framework for addressing the risks of climate change."

Related: Trump's right: A coal mine is opening soon

Murray's effuse praise for Trump shows how the mood in coal country has improved under Trump, who received enormous support in last November's election from Rust Belt communities. The president's speech last week on the Paris decision declared the "mines are starting to open up." Trump pointed to the opening of a coal mine in western Pennsylvania later this week.

But Murray isn't as optimistic about an immediate resurgence of coal jobs as Trump. He said the withdrawal from the Paris accord alone won't be enough to put the miners back to work.

"He can't bring it back overnight, but it will help," Murray said.

Trump has sought to relax the burden on coal miners by beginning to unwind Obama's Clean Power Plan. Murray Energy, which had sued the Obama administration to fight the plan, estimates that Trump's efforts to unwind the environmental rules have already saved 25,000 coal jobs.

Government statistics show little sign of a coal jobs boom, though the onslaught of layoffs has eased. The U.S. has added 1,700 coal mining jobs since the end of October, according to the Bureau of Labor Statistics. There are now 51,000 coal mining jobs, down from over 89,000 at the end of 2011.

Related: Female coal miners react to Trump's decision on climate deal

But many believe Trump's deregulation alone can't create a coal renaissance. That's because the abundance of cheap natural gas as a cleaner alternative to coal has been the biggest driver of coal's downfall, according to a recent Columbia University research report.

Even Gary Cohn, Trump's top economic adviser, praised natural gas as "such a cleaner fuel" and said "coal doesn't even make that much sense anymore as a feedstock."

Murray argues natural gas is just one factor, along with unfair regulation and government support for wind and solar energy.

"Gary Cohn and Columbia University are wrong," Murray said.

He insists that on a level playing field, coal can survive just fine, despite the 18% plunge in natural gas prices this year.

"Give me the ball and I'll compete against natural gas with our coal all day long," he said. "We just need to get the government out of picking winners and losers in the energy industry."