The U.S. government's AAA credit rating—the highest possible—on its long-term debt is on a downward slope according to Fitch, the third-largest credit rating agency.

This "rating watch negative" is a result of the emergency measures the government has been using to manage the nation's finances under the debt limit which will run out Thursday. 

"Although Fitch continues to believe that the debt ceiling will be raised soon the political brinkmanship and reduced financing flexibility could increase the risk of a U.S. default," the agency said. If the nation's ability to borrow money to pay bills does not increase, "the U.S. risks being forced to incur widespread delays of payments to suppliers and employees, as well as social security payments to citizens - all of which would damage the perception of U.S. sovereign creditworthiness and the economy."

Fitch's decision on whether to lower the AAA rating on U.S. debt could be made by the end of the first quarter. 

A similar debt showdown happened in 2011, and stripped the U.S.'s credit rating from AAA to AA+. 

A Treasury Department spokesperson said the announcement "reflects the urgency with which Congress should act to remove the threat of default hanging over the economy," CNN reports. 

Reach Staff Reporter Cortney Riles here. Follow her here.