A Senate panel postponed a vote scheduled for Thursday on approving John Bolton as U.N. ambassador, a job he has held temporarily since last year when President Bush appointed him over Democratic opposition.

Senate Foreign Relations Committee Chairman Richard Lugar, R-Ind., gave no reason for the delay and did not say when the vote would be held. Bolton had been opposed by many Democrats but was expected to be confirmed by the Republican-led panel.

Lugar said he removed the nomination from the agenda of Thursday's committee meeting after conferring with several senators.

His approval by the committee would pave the way for a confirmation vote on the Senate floor.

Bush temporarily installed Bolton as U.N. ambassador on Aug. 1 of last year while Congress was in recess, an appointment that will expire in January. The recess appointment, provided for by the Constitution, came after Democrats blocked repeated attempts by GOP leaders to grant Bolton Senate confirmation.