It can be notoriously difficult to pin down Donald Trump on the finer points of policy. But on Monday morning, the Republican presidential nominee put forth a surprisingly specific proposal: He is going to cut “70 to 80 percent” of federal regulations if he wins the White House.

Trump, lagging badly in the polls, made his anti-regulatory vow while speaking at a farmers’ roundtable in Boynton Beach, a town in the must-win state of Florida. The real estate mogul did not explain how his administration would determine which rules to axe, or how they would go about accomplishing such an unprecedented rollback through executive fiat.

“We want clean air, we want clean water,” Trump said. “But we have and you have situations and regulations, which we’re gonna cut ― we will probably cut 70 to 80 percent of the regulations, OK?”

The Republican nominee told farmers that the regulatory oversight of the Environmental Protection Agency, a favorite target of his, was simply too much to bear. The federal agency that enforces clean air and water laws has been a “total disaster,” and regulations on the whole “have been a total catastrophe,” he said.

Trump clarified, however, that he likes fresh air as much as the next person. “Look, we all believe in environment,” he said. “I mean, my primary thing with the environment ― immaculate air, beautiful clean air, and crystal clean water. That’s it. Once you go beyond that, you start to lose all of us, OK?”

Facing an increasingly narrow path through the electoral college, Trump has been banging the anti-regulation drum hard in recent days, starting with his “contract with the American voter.” In that agenda, Trump says that he will require that two regulations be repealed for every new one that goes into effect, offering no rationale for that seemingly arbitrary ratio.

A President Trump might be surprised by how difficult it would be to repeal 70 to 80 percent of federal regulations. A president could undo certain regulations that are established through executive action, and effectively weaken others by choosing not to enforce them much. But businesses mostly face regulations that have been established by Congress, through laws like the Clean Water Act and the Clean Air Act. Congress would therefore have to undo such laws.

Trump has gone so far as to claim that the nation’s coal barons are practically starving, thanks to regulations.

“I have friends that own the mines. I mean, they can’t live,” Trump said at a Pennsylvania campaign event in August. “The restrictions environmentally are so unbelievable where inspectors come two and three times a day, and they can’t afford it any longer and they’re closing all the mines. … It’s not going to happen anymore, folks. We’re going to use our heads.”