WASHINGTON (AP) - The Government Accountability Office has denied motions filed by Northrop Grumman Corp. and the Air Force to toss key portions of Boeing's protest of a $35 billion aerial tanker contract, Northrop Grumman said late Wednesday.

The GAO, which has until June to rule on the Boeing Co. protest, would not comment. And Air Force officials could not be reached immediately for comment.

Boeing filed a formal protest of the air tanker refueling contract with the GAO on March 11. In late February, Air Force officials awarded the contract to Northrop Grumman and European Aeronautic Defence and Space Co., parent of Boeing rival Airbus. The job of building 179 aerial refueling tankers is the first of three Air Force contracts worth as much as $100 billion over 30 years to replace its fleet of nearly 600 tankers.

A Boeing spokesman said the company is supplementing its protest. And a Northrop spokesman said the company looks forward to helping the Air Force defend its selection.