EU leaders to review 'Spitzenkandidat' process

"Once the new European Commission is effectively in place the European Council will consider the process for the appointment of the president of the European Commission for the future, respecting the European treaties," the statement says.

Under the Spitzenkandidat system, used for the first time this year, the top candidate of the most popular party after the EU vote - in this case Juncker of the centre-right EPP - is nominated for the post.

It represents a stretching of the wording in the EU treaty, which only binds EU leaders to take election results into account.

However, leaders are also aware that they contributed to this being the first EU summit where they had no free hand to choose a commission president.

They went along with the process of political parties nominating candidates only to see it taking off and becoming more cemented as the various candidates attended debates and toured member states, while presenting themselves as running for office.

This meant that Juncker was nominated although leaders had privately expressed concern about whether he is the right person for the job.

EU Council president Herman Van Rompuy, himself an opponent of the system, acknowledged this dilemma after the summit.

"Most of the leaders belonged to European parties and they were involved in the process of appointing future candidates for the European Commission. So we have to take this into account. And this was also reflected in the discussions," he said.

But he added: "Is everybody happy with the procedure? That is something else."

British PM David Cameron, who led a strong campaign against Juncker, said "this process developed a momentum of its own. We need to ask ourselves how this happened."

He added that the dynamics of the system means it is "impossible" to choose a sitting head of state, "we have to wait for someone who has retired".

German Chancellor Angela Merkel, who from the outset was against the new system but retreated in the face of a backlash by domestic press, also said the issue would have to be revisited.

However the European Parliament was jubilant, indicating that it is likely to cement the Spitzenkandidat process when it comes to the next EU election in 2019.

"Juncker's proposal to be next Commission President marks a turning point for European democracy," said the EP's current chief Gianni Pittella.

“The voice of the European citizens has been heard," said the centre-right EPP party chairman, Manfred Weber, with many parliamentarians noting the 2014 vote for the first time provided a much-needed link between EU citizens and Brussels by politicising the selection process.