The U.S. Constitution gives Congress the power to write laws regulating commerce and financial markets — including interest-rate limits on credit cards. Trump has called for a one-year cap at 10%, but no such law currently exists, and a presidential proclamation alone doesn’t change private-sector interest rates.

I think there's been an expectation that banks and credit card issuers probably would respond to this through products, new products that offer, you know, 10% rates or some sort of relief to card hold...

Some of America’s top bankers are warning that the president’s cap on credit card interest rates would prove disastrous for lower-income consumers and the US economy — not to mention their profits.