The Bavarian MEP Weber failed to win the backing of EU national leaders who in three days of summit wrangling instead settled on German Defence Minister Ursula von der Leyen as the nominee to replace Jean-Claude Juncker.

The deal has upset members of the European Parliament, who wanted major EU executive posts to be filled by the top candidates of the biggest parliamentary party blocs to emerge from the May election.

"There were backroom discussions and night-time sessions in which the Macron and Orban axis prevailed and the top candidate principle was dismantled," Weber told Germany's Bild daily.

"There were powerful forces who would not accept the election result" of the May 26 vote, said Weber, who had been the top candidate of the conservative European People's Party (EPP) bloc, which remains the biggest.

"This is not the Europe I imagine," said Weber, charging that Macron's collaboration with Orban on the issue had left a "shambles".

He argued that, although Macron had during the election campaign attacked Hungary's right-wing populist leader, "suddenly they're working together, damaging a democratic Europe".

Macron had long made clar he considered Weber too inexperienced for the job.

Weber called this claim "absurd" and added that "the voters should decide on the qualifications, no-one else".

Von der Leyen on Thursday made her first trip to Brussels to meet Juncker and, as she wrote on Twitter, seek "smart advice" as she prepares her plan for the next five years.

She must still win the approval of the highly fragmented European Parliament to become commission president.