Democrats in the US Senate have again blocked the nomination of John Bolton as UN ambassador.
Republican leaders fell six votes short of the 60 votes needed to end a filibuster and advance the nomination to a confirmation vote.
The Senate vote of 54-38 to try and overcome the filibuster came after Mr Bush called for an immediate up-or-down vote on Mr Bolton's nomination.
"Well, put him in. If they're interested in reforming the United Nations, they ought to approve John Bolton," Mr Bush said at a news conference with European leaders.
It was the second failed attempt by Senate Republican leaders to bring the contested nomination to a vote. Mr Bush may appoint Mr Bolton to the post during an upcoming congressional recess to bypass lawmakers and put him in the job without a confirmation vote.
But Senator Pat Roberts, a Kansas Republican who heads the Senate Intelligence Committee, said the country would be better served by a UN ambassador who was confirmed by the Senate.
Democrats are demanding that the White House release information they say is important to the Senate's review of his fitness for the job. They want to know whether Mr Bolton, the top US diplomat for arms control, misused intelligence and bullied analysts who did not conform to his hard-line views.
Mr Bush and his Republican allies in the Senate see him as the right man to press for UN reforms.