Most European leaders were on the same page at an informal summit to claw back their says in picking the successor to Jean-Claude Juncker, incumbent president of the European Commission.

As next European Parliament(EP) election slated for May 2019 is drawing closer, the move dealt a blow to political groups in the EP, as well as Juncker, who adamantly backs the so-called "lead candidate" system.

Speaking at the press conference following the summit, European Council President Donald Tusk said the leaders of member states agreed that they cannot guarantee in advance they will propose one of the "lead candidates" for next president of the European Commission.

"Their no automaticity in this process, " he stressed, referring to the "lead-candidate" system to pick the president of the European Commission.

Under the system, each political group in the European Parliament (EP) nominates a candidate for the top-tier post in the run-up to the EP election.

The candidate of the party group which scoops the most seats in the EP is to be nominated by the European Council and approved by the EP by a majority of votes.

The "lead candidate" system, firstly put into place in the 2014 EP election, is not enshrined in the 2009 Lisbon Treaty, which only ambiguously stipulates that the European Council should propose to the EP a candidate "taking into account the elections to the EP and after having held the appropriate consultations."

A number of EU states have raised eyebrows at the "lead candidate" system, worrying that "the pool of potential candidates would become more limited, and the politicization of the Commission," according to a note released by the European Council days ahead of the summit.

However, Commission President Juncker, who as the lead candidate of the European People's Party secured the post in 2014, has time and again thrown his weight behind it, arguing that the winner of the candidate has a "double legitimacy" with the endorsement from the European Council and the EP.

When it comes to the line-up of EP in the post-Brexit era, Tusk said leaders saw eye to eye on the principle of "fewer members state should mean fewer seats", and gave their nods to a proposal put forward by the EP to cut seats.

The EP has proposed that the 27 of the 73 seats currently allocated to Britain be redistributed to 14 member states "to reflect demographic changes." The EP also suggested cutting the number of seats from 751 to 705.

But leaders were at odds over the idea of "transnational list", which is backed by French President Emmanuel Macron. "Leaders will come back to the issue in the future," said Tusk, without going into details.

According to the note released by the European Council, the idea is put on the back burner as it would "require modification of the Electoral Act, which must be adopted at least one year before the elections."

The "transnational list" also requires the unanimity of EU member states, the EP's consent and the approval by all the national parliaments.

To Juncker's dismay, again, European leaders also gave their cold shoulders to his proposal of merging the posts of the president of the European Council and European Commission.

Tusk said all other leaders "have no appetite to take this forward. above all, because it will substantially reduce the role of member states in the EU."

Standing alongside Tusk at the press conference, Juncker conceded that the summit atmosphere was friendly except when leaders touched on this issue.

The summit was held in an EU27 format without the participation of Britain, as the issues debated will only come into play after Britain's withdrawal of the bloc.