Secretary of Defense Robert Gates says he is “disappointed” at the Senate's failure to repeal “Don't Ask, Don't Tell.”

“I was disappointed in the Senate vote, but not surprised,” Gates told reporters en route from the Middle East.

On Thursday, Republicans blocked a measure that would repeal the law that bans gay and bisexual troops from serving openly. Maine Senator Susan Collins crossed the aisle to vote with all but one Democrat, West Virginia Senator Joe Manchin. Blanche Lincoln, a senator from Arkansas who voted against the measure in September, arrived too late to cast her vote, but told reporters that she would have voted for repeal.

The measure will face a steeper incline next year when Republicans, who mostly support the policy, regain control of the House and increase their numbers in the Senate.

Gates warned that Congressional failure to repeal the law would leave the military “at the mercy of the courts.”

“The fact remains, though, that there is still roughly a week left in the lame-duck session, and so I would hope that the Congress would act to repeal 'Don't Ask, Don't Tell.' If they are unable to do that, then as I've indicated in testimony and talking with you all, my greatest worry will be that then we are at the mercy of the courts and all of the lack of predictability that that entails.”

Gates was among the military leaders who testified in favor of repeal before a Senate panel. He urged Congress to repeal the law before the courts force its immediate end. A judge's order that called the law unconstitutional forced the military to end enforcement of the policy for eight days in October. The Obama administration convinced an appeals court to put the ruling on hold as the case is being appealed.

Gates called the ruling a “wake-up call” for the military.

Repeal is “something that I think needs to be done very carefully, very thoughtfully and to take the time necessary to prepare. And so as I said, the way we get that time most assuredly is with the legislation that's before the Congress today.”

President Barack Obama also urged the Senate to schedule a second vote before the end of the session.