Senate Republicans have blocked an effort to repeal the law banning gays from serving openly in the US military.
The partisan vote was a defeat for gay rights groups who saw the provision in a defense authorization bill as their last chance any time soon to overturn the law known as "don't ask, don't tell."
Democrats fell short of the 60 votes needed in the 100-member chamber to advance the legislation, which authorized $726 billion in defense spending.
Republican Sen. Susan Collins had been seen as the crucial 60th vote because she supports overturning the military ban. But Collins sided with her party colleagues in arguing that Republicans were not given sufficient leeway to offer amendments to the wide-ranging policy bill.