Chief executives from the nation's largest financial firms on Thursday pressured the White House and Congress to reach a deal on the debt ceiling and deficit reduction, saying the consequences of inaction "would be very grave."

JPMorgan's Jamie Dimon, Goldman Sachs' Lloyd Blankfein and Bank of America's Brian Moynihan, among others, said in a letter that an agreement needs to be reached this week.

"A default on our nation's obligations, or a downgrade of America's credit rating, would be a tremendous blow to business and investor confidence -- raising interest rates for everyone who borrows, undermining the value of the dollar, and roiling stock and bond markets -- and, therefore, dramatically worsening our nation's already difficult economic circumstances," the letter said.