Moody's Investors Service - the body that cut the standing - said that the move was also made because of fears a principal on outstanding bonds might also be skipped.
Although the ratings agency - which has a presence in 26 countries - noted the possibility of a downgrade remains slim, the action is likely to increase pressure on lawmakers in the nation to up the government's $14.3 trillion debt limit.
In a statement, Moody's claimed there is a "rising possibility that the statutory debt limit will not be raised on a timely basis, leading to a default on US Treasury debt obligations".
The US has been rated at its current stance of Aaa since 1917 and any downgrade would likely see this reduced to Aa.
By Gary Cooper