The US Ambassador to the United Nations, John Bolton, is to step down in the coming days.
Mr Bolton was appointed on a temporary basis by President George W Bush while Congress was not sitting, and therefore unable to hold hearings to ratify the nomination.
It is reported that Mr Bolton has told Mr Bush he does not wish to be renominated, as would be the normal procedure.
A White House spokeswoman said the president had reluctantly accepted the decision.
In 2005, when he was originally nominated, the Democratic minority in Congress prevented Mr Bolton’s ratification by a filibuster – refusing to let the debate come to a vote before the time available ran out.
Mr Bush then made what is termed a 'recess appointment', bypassing the ratification process, but that could only last for one full following session of Congress.
It is not known when President Bush will announce his choice to replace Mr Bolton.
