Oil fell, headed for the first weekly decline in five, on concern a failure to reach a deal on raising the U.S. debt limit may cause the nation to default, threatening the economy of the world’s biggest crude consumer.

Futures slipped as much as 0.6 percent after House Speaker John Boehner delayed a planned vote on debt-limit legislation as Senate leaders stood ready to kill the measure should it get to their chamber. Prices also dropped before a report forecast to show the world’s largest economy grew at the slowest pace in a year. U.S. crude stockpiles rose for the first time in eight weeks last week, Energy Department data showed July 27.

“All eyes are focused on the U.S. debt,” said Jonathan Barratt, a managing director of Commodity Broking Services Pty in Sydney, who predicts oil in New York will average $100 a barrel this year. “We did see a build in inventories. If it becomes more of a trend rather than a one-off, that’s a worry.”

Crude for September delivery fell as much as 55 cents to $96.92 a barrel in electronic trading on the New York Mercantile Exchange. It was at $97.05 at 3:15 p.m. Singapore time. Yesterday, the contract rose 4 cents to $97.44. Prices are down 2.9 percent this week and 1.7 percent higher the past month.

Brent oil for September settlement on the London-based ICE Futures Europe exchange was at $117.46 a barrel, up 10 cents. The European benchmark contract was at a premium of $20.45 a barrel to New York futures, compared with a record close of $22.63 on July 14.

Crude in New York is extending losses as prices slide below the 50-day moving average. Front-month futures have settled for more than a week above this indicator, at $97.33 today. A breach of technical support usually means prices will continue to fall.