JPMorgan Chase CEO Jamie Dimon on Wednesday advocated for a test of President Donald Trump’s proposed 10% cap on credit card interest rates in two U.S. states: Vermont and Massachusetts.

Dimon, speaking on a panel at the World Economic Forum at Davos, Switzerland, addressed a question about Trump’s order for banks to voluntarily limit their interest rates for a year. The president had called for the lower rates to take effect Jan. 20.

Several large credit card lenders contacted by CNBC on Tuesday said they had made no changes to their interest rates, but they all declined to be identified as defying Trump’s proposal.

“It would be an economic disaster,” Dimon said Wednesday. “In the worst case, you’d have a drastic reduction of the credit card business” for 80% of Americans, he said.

Dimon then said he had a “great idea” to help quell disagreement over the proposed card cap, suggesting that the U.S. government impose the pricing controls on Americans in just two states.

Vermont and Massachusetts are the home states of Sens. Bernie Sanders and Elizabeth Warren, respectively, both of whom support a bill capping card rates at 10% for five years. Dimon didn’t mention the lawmakers by name Wednesday.

The U.S. government “should force all the banks to do it in two states, Vermont and Massachusetts, and see what happens,” Dimon said, drawing laughter from the WEF audience.

Dimon said “the left” and people who argue for price controls “will learn a real lesson, and the people crying the most won’t be the credit card companies,” he said.

“It’ll be the restaurants, the retailers, the travel companies, the schools, the municipalities, because people miss their water payments,” he said. “It would be something else to watch.”

Dimon added that JPMorgan was planning on giving the Trump administration its analysis on what would happen under a national credit card rate cap.

“I think it’s wrong to for the government to get involved extensively in pricing of stuff, but I got to deal with the world I got,” Dimon said.