President Trump on Monday admitted that repealing and replacing ObamaCare — one of his signature campaign promises — was going to be a lot tougher than he thought.

“I have to tell you, it’s an unbelievably complex subject,” Trump said in a meeting with the nation’s governors.

“Nobody knew that health care could be so complicated.”

He added that overhauling the tax code was a “tiny little ant” compared to remaking the Affordable Care Act, especially with more people saying they like the plan than previously.

A Wall Street Journal/NBC News poll from last week said that 43 percent of voters liked the law while 41 percent thought it was a bad idea.

Trump theorized that ObamaCare was increasing in popularity not because people liked it, but instead because its end was near.

“People hate it, but now they see that the end is coming, and they’re saying, ‘Oh, maybe we love it,’” Trump said, without further explanation. “There’s nothing to love. It’s a disaster, folks.”

He then speculated that it might be better for him politically if he just allowed the system to “implode.”

“Let it be a disaster, because we can blame that on the Dems that are in our room — and we can blame that on the Democrats and President Obama,” Trump told the National Governors Association at the White House.

“But we have to do what’s right, because ObamaCare is a failed disaster.”

Governors have raised concerns that the changes could undermine their efforts to expand Medicaid in their states and leave them stuck with ballooning payments.

Trump met later Monday morning with health insurance executives, some of whom are worried that the uncertainty over the health care law’s future is spilling into the marketplace.

Without offering specifics about what he wants in a replacement package, Trump called on the executives to work with the government on a way forward.

“We must work together to save Americans from ObamaCare,” he said.

Sen. Charles Schumer, meanwhile, said Monday the odds are “very high” that the GOP won’t be able to muster enough votes to repeal ObamaCare.

With AP