Tony Blair is out of the race to become the first President of the EU Council, Sky News reported.
Sky's political editor Adam Boulton said Gordon Brown had decided that support for the ex-PM was insufficient for him to back him at a meeting of EU leaders to decide the appointment this evening.
The Prime Minister will instead back former leader of the House of Lords Baroness Ashton for the role of EU High Representative, the Web site reported.
"We should stress that Tony Blair has never said that he was a candidate, so technically he has not been rejected," Boulton said, according to Sky News.
"However, it is known that Gordon Brown, his closest and most complicated friend in politics, was advocating him for the job and it is unlikely he would have done it against the will of Blair."
"This is a political setback for Blair."