Democrats failed Thursday to cinch a procedural deal with Republicans in the waning days of the lame-duck session. The 57-40 test vote fell three votes short of the 60 needed to advance.
The vote ends months of political wrangling on the bill and makes congressional action on the repeal provision unlikely any time soon.
The 1993 law bans gay troops from publicly acknowledging their sexual orientation. A repeal provision was included in a broader defense policy bill and passed last spring in the House.