Ratings agency Fitch has placed its top rating on US debt under review for a possible downgrade.
The agency put the AAA credit rating under review, as the deadline to raise the US borrowing limit drew closer.
According to the BBC, the move comes after Democrats rejected a plan by the Republican-led House of Representatives as an attempt to appease a small group of conservatives.
US Treasury spokeswoman Brandi Hoffine said that announcement by Fitch reflects the urgency with which Congress should act to remove the threat of default hanging over the economy, the report said.
While Fitch said it expected the debt limit to be raised soon, it added that 'political brinkmanship' and 'reduced financing flexibility could increase the risk of a US default,' it added.
