Senate gay marriage ban 'to fail'
Republican senators have admitted their attempt to change the US constitution to ban gay marriage looks set to fail.
Their amendment faces a test vote on Wednesday, but looks unlikely to gain the support of 60 senators that it needs to progress to the next stage.
President Bush has urged the Senate to support the amendment, while his Democratic rival John Kerry opposes it.
Gay marriage has become a key issue in election year, after some states and towns moved to make it legal.
In the face of probable defeat, Republican senators are hoping to gain a simple majority in the vote.