The ratings agency Moody's affirmed the U.S. credit rating at "Aaa" on Wednesday. The outlook is "stable".

Moody's warned that there could be uncertainty "from the contentiousness of the political process".

"On a positive note, the process has introduced an element of spending restraint which has contributed to deficit reduction ahead of our expectations in recent years," Moody's Senior Vice President Steven Hess said.

"The Aaa rating is buttressed by a large and diverse economy, a strong record of GDP and productivity growth, and the status of the dollar and the US Treasury bond as global reserve currency and benchmark, respectively," Moody's concluded.