Moody’s Investors Service on Friday put the U.S. government’s pristine credit rating on a negative outlook, raising the possibility of another downgrade of American debt.

The credit rating agency cited risks to the U.S. fiscal outlook — namely, higher interest rates “without effective fiscal policy measures to reduce government spending or increase revenues.”

“Continued political polarization within [the] US Congress raises the risk that successive governments will not be able to reach consensus on a fiscal plan to slow the decline in debt affordability,” credit rating agency Moody's said.