Outgoing European Commission President Jean-Claude Juncker on Friday criticised as "not very transparent" the way European Union leaders selected the nominee to replace him.

After three days of marathon talks, the European Council rejected the_ Spitzenkandidat_ system to nominate German Defence Minister Ursula von der Leyen to replace Juncker when his term expires on November 1.

Under this system — through which Junker himself had been appointed — each group in the European Parliament had nominated a lead candidate during the election campaign, who was meant to assume the Commission presidency should they end up with the largest number of seats.

During a joint press conference with Finnish Prime Minister Antti Rinne in Helsinki on Friday, Juncker said the nomination process "was not very transparent", adding that "it's a vision to come back to what unfortunately didn't become a tradition."

He then joked: "I said in the European Council the other day that I always had the impression that I would add to history. But not like that, because I am a very unique guy. I was the first and the last Spitzenkandidat."

Juncker's comments come a day after he met with von der Leyen, whom he described as "a true European"

"We are on the same page when it comes to speaking up for the European Union's interest," he posted on Twitter.

Manfred Weber, the German MEP who had been the European People's Party lead candidate, told the Bild newspaper on Thursday that he is "very disappointed" EU leaders had ignored the Spitzenkandidat system and blamed French president Emmanuel Macron and Hungarian Prime Minister Viktor Orban, both vocal opponents of the system.

"There were backroom talks and late-night sessions in which the Macron and Orbán axis prevailed and the Spitzenkandidat system was dismantled," he said, adding however that he "will support Ursula von der Leyen."

MEPs will vote on July 15th on whether to approve von der Leyen's nomination. If they reject it, the European Council will then have a month to propose another name.

READ MORE: MEPS blast Tusk over von der Leyen's controversial nomination