Bill Clinton has blasted President Obama’s signature piece of legislation — ObamaCare — as “the craziest thing in the world.”

“You’ve got this crazy system where all of a sudden, 25 million more people have health care, and then the people who are out there busting it, sometimes 60 hours a week, wind up with their premiums doubled and their coverage cut in half and it’s the craziest thing in the world,” the former president railed at a rally in Michigan on Monday.

Clinton also said the system is hurting moderately successful small businesses — ones that aren’t doing poorly enough to be subsidized and fall just above the line.

“On the other hand, the current system works fine if you’re eligible for Medicaid, if you’re a lower-income working person, if you’re already on Medicare or if you get enough subsidies on a modest income that you can afford your health care,” Clinton said.

“But the people getting killed in this deal are the small-business people and individuals who make just a little bit too much to get any of these subsidies,” he added.

After the scathing attack, Clinton sought to tone down some of his ObamaCare criticism while stumping for his wife in Ohio on Tuesday. Like Hillary, he said the health-care law is a positive first step that needs improving.

“The Affordable Health Care Act did a world of good and the 50-something efforts to repeal it that the Republicans have staged were a terrible mistake,” Clinton said.

“But there’s a group of people — mostly small-business owners, and employees who make just a little too much money to qualify for Medicaid expansion or for the tax incentives — who can’t get affordable health-insurance premiums in a lot of places,” he said.

“[Hillary] has proposed to take the next step in this and do what the president tried to do the first time and she supported, which is to allow people 55 and over to buy into Medicare and allow others to have a public option that looks like expansion of Medicaid they can afford. It’s the right thing to do.”

But in quelling one firestorm, Bill Clinton ignited another — throwing Bernie Sanders under the bus in an improptu response to a Black Lives Matter heckler as he defended his own controversial 1994 crime bill.

Clinton was interrupted by a protester shouting that he won’t vote for someone who sends thousands of people to prison.

“Hillary didn’t vote for the ’94 crime bill even though Senator Sanders did,” the former president shot back, as the heckler was removed from the rally.

Sanders has been campaigning for Clinton after losing the Democratic nomination to her.

The former president said it was his wife who was the first candidate to speak up about changing incarceration policies.

“The facts are difficult there,” Clinton said in his rebuttal. “You ought to think about it. If you’re really upset, that means you’re also upset that we had a 25-year low in the crime rate, a 33-year low in the murder rate — and, listen to this: a 67-year low in the rate of people being killed by illegal gun violence. I’m pretty proud of that, and I think that was worth fighting for.”

With Wire Services