“In my opinion we will not default,” JPMorgan CEO Jamie Dimon said during a panel discussion at the annual meeting of the Institute of International Finance, a bank trade group, in Washington. “I think any responsible person I know including in government knows that. I think it would ripple across the global economy in ways you couldn’t possibly understand.”

The Treasury Department has warned that Congress must lift the debt ceiling by Oct. 17 when the U.S. is slated to exhaust its borrowing authority.

Other leading bankers at the IIF event joined in warning about the consequences of Washington not reaching a deal.

“It would be utterly catastrophic,” said Deutsche Bank Co-Chair Anshu Jain, stressing the importance of the U.S. dollar in international finance. “This would be a rapidly spreading fatal disease.”