A “fired up” President Obama vowed Monday that Donald Trump will find it’s not so “easy” to roll back his myriad regulatory policies, previewing a long fight ahead between his allies and majority Republicans taking control next year.

President-elect Trump has vowed to repeal and replace ObamaCare, while canceling “every unconstitutional executive action, memorandum and order issued by President Obama.”

Trump also pledges to sharply increase oil and gas drilling on federal lands while opening up offshore drilling in the Atlantic Ocean and other areas where it is blocked. Further, he wants to repeal the Clean Power Plan, Obama's signature effort to limit carbon pollution from coal-fired power plants. The plan -- the linchpin of Obama's strategy to fight global warming -- is currently on hold awaiting a court ruling.

It is all but assured that Trump, together with the Republican-controlled Congress, will try anew next year to repeal or significantly change ObamaCare, formally known as the Affordable Care Act.

But in a conference call with Democrats Monday, Obama warned that unraveling his policies is “not as easy” as some say. Plus, he said even if the Trump administration rolls back 15-20 percent of his work, they’re still “80 percent” ahead.

The outgoing president did not specify what his post-presidency role will be, but hinted he’d be involved and said he’d be “working shoulder to shoulder” with Democrats for “many years.”

Obama said he’d be in a position to make the case for why policies like ObamaCare should be preserved and said, “I’m still fired up,” referencing his 2008 campaign catch phrase.

In an earlier White House press conference before he left the country for his final overseas trip as president, Obama specifically addressed Republican plans to upend ObamaCare.

“Now that Republicans are in charge, they got to take a look and say, let's see. We got 20 million people who have health insurance who didn't have it before,” he said. “Health care costs generally have gone up at a significantly slower rate since ObamaCare was passed than they did before, which has saved the federal Treasury hundreds of billions of dollars.”

Some Democrats, though, have acknowledged a need to at least change the system to address rapidly rising premiums and other issues.

Trump has indicated a willingness to keep certain elements of the law in place.

His potential picks for key positions, meanwhile, signal big changes ahead for environmental and energy policies.

Those under consideration for energy secretary include Harold Hamm, an Oklahoma oil tycoon and leading proponent of fracking, and North Dakota Rep. Kevin Cramer, an early Trump supporter from a major oil drilling state, according to transition planning documents obtained by The Associated Press.

Venture capitalist Robert Grady, who worked in President George H.W. Bush's administration, is listed as a contender to lead both the Energy and Interior departments.

It's unclear whether the list is exhaustive or has been reviewed by Trump. The Republican is in the early stages of setting up his administration.

A coalition of conservative states has challenged both the Clean Power Plan and a controversial water rule, which expanded the definition of waters protected under the Clean Water Act to smaller non-navigable waters and seasonal tributaries.

The administration says the rule would safeguard drinking water for 117 million people, but Republicans and some Democrats representing rural areas say the regulations are costly, confusing and amount to a government power grab. Federal courts have put the rules on hold as judges review lawsuits.

The Associated Press contributed to this report.