From Erika Bolstad in Washington D.C. --

Sen. Lisa Murkowski, who said Wednesday she supports the repeal of the "don't ask, don't tell" ban on gays in the military, voted against the underlying defense authorization bill that includes language to overturn the prohibition.

The vote failed 57-40. Democrats needed 60 votes to proceed with debate on the bill, which includes language that would lead to the policy's reversal. Murkowski and several other Republicans who support the repeal of "don't ask, don't tell" had said they would vote to move the bill forward for debate -- but only if they were allowed additional time for debate and more leeway to propose amendments.

Wednesday, Murkowski said in a statement that America is "the loser when it denies those who are willing to make the great sacrifices demanded of our men and women in uniform the opportunity do so on grounds of sexual orientation."

But she also warned her support of the underlying legislation was conditional, and she wouldn't vote to move forward on debate of the defense bill unless Democrats gave the GOP additional time to debate and amend it.

All 42 Republican senators said in a letter to Senate Majority Leader Harry Reid last week that they wouldn't agree to let any legislation come to a vote until they had considered tax cuts and government spending bills.

Sen. Mark Begich, D-Alaska, supports repeal of the "don't ask, don't tell" policy, and voted to proceed with debate on the bill.