The US Senate blocked the repeal of a ban on gays serving openly in the military yesterday in a procedural vote, indefinitely delaying consideration of the measure.

In the 56-43 vote, President Barack Obama’s Democrats fell four votes short in the 100-seat Senate in a bid to overcome what is known as a filibuster.

The tactic had been deployed by the rival Republicans to prevent debate on the repeal of the “Don’t Ask Don’t Tell” measure.

The text was considered the best compromise at the time when it was adopted in 1993 to resolve the thorny controversy of gays in the US military, but since then the policy has been increasing challenged by critics who say it is discriminatory.