Crude prices were down in Asian trade, with investors fretting over the state of the US economy as lawmakers scrambled for a compromise to avert a devastating default, analysts said.
New York's main contract, light sweet crude for delivery in September, fell 45 cents to $US96.95 per barrel.
Brent North Sea crude for September delivery shed 15 cents to $US117.28.
A drawn-out political impasse in the United States as polarised politicians struggled to find a mutually agreeable middle ground over a debt solution for the world's largest oil consumer was exacting its toll on traders.
"Prices remain largely range-bound... as a result of the economic uncertainty, particularly with regard to the US budget impasse," said Sanjeev Gupta, who heads the Asia-Pacific oil and gas practice at Ernst & Young.
Congress was due to consider Republican Speaker John Boehner's plan to raise Washington's $US14.3 trillion debt ceiling although it looked doomed to fail due to a White House veto threat.
US lawmakers were privately hunting for a compromise to avert a debt default due to kick in on August 2.
