The economic bloc will take a decision on the new EU officials, following the elections that shook up traditional alliances.
European leaders descended on Brussels on Tuesday to begin the hunt for a new generation of top EU officials in the wake of elections that shook up traditional alliances.
The key job to be filled is that of president of the European Commission, the union's powerful chief executive, a five-year post currently held by Jean-Claude Juncker.
Under EU treaty law, the European Council of 28 national leaders nominates a commission president, then the new 751-member parliament ratifies their choice.
But the procedure, while seemingly straightforward, masks a complex power struggle between rival states and ideological blocs and between the leaders and parliament itself.
'Game of Thrones'
Juncker's deputy and the centre-left challenger for the top job, former Dutch minister Frans Timmermans, compares the ruthless intrigue to "Game of Thrones".
The tussle kicks off on Tuesday when European Council President Donald Tusk hosts the EU leaders for a summit dinner in Brussels to lay out the ground rules.
Ahead of the summit, party and national leaders met in various smaller groups to scheme, and the heads of the main party blocs in the parliament held closed-door talks.
Many in Brussels argue that the European project is best served by a "political commission" headed by a president with a mandate from the parliament.
But most national leaders think the union's legitimacy derives from its member states and that the Council should be able to pick one of their own – someone with leadership experience.
The results of the EU elections did not strengthen parliament's hand – except perhaps for the boost of the larger than expected voter turnout.
While a threatened surge of eurosceptic and far-right populist parties was largely contained, the pro-Europe centre was fragmented, with liberals and Greens gaining ground.
In previous years, a coalition of the socialist S&D and the conservative EPP was able to wield a majority. Now they cannot govern without the liberal ALDE or the Greens.
And this complicates their choice of a "spitzenkandidat" – or lead candidate for the Commission.
The EPP insists that as it is the biggest bloc, its candidate Manfred Weber must be Commission president, but it lost around 40 seats in the election, only narrowly remaining the largest group.
Anyone but Weber?
But Weber, who has spent the last 15 years in the European Parliament, is seen as short on charisma, has no executive experience – and is opposed by French President Emmanuel Macron.
Eight of the 28 EU leaders hail from EPP parties, but Hungarian premier Viktor Orban's Fidesz is suspended from the group and Austrian Chancellor Sebastian Kurz was ousted by parliament on Monday.
Timmermans, a centre-left Dutchman with more executive experience, will have the S&D's backing and ALDE, while dubious about the process, could back Margrethe Vestager.
The Danish competition commissioner might win Macron's support while Germany's Chancellor Angela Merkel backs Weber.
Macron met Spain's Prime Minister Pedro Sanchez for dinner on the eve of the summit.
Afterward, a Spanish government source said, "The new posts should reflect the new majority in parliament, which is not only the EPP but includes social democrats and liberals."
Udo Bullman said there was "broad agreement" among the parties agreed to stand by the spitzenkandidat process.
But ALDE leader Guy Verhofstadt declared that the system died when the EPP refused to give it democratic legitimacy by backing the creation of transnational parties.
"A Spitzen-candidate that you cannot vote for in the whole of Europe is simply not serious," the former Belgian PM tweeted, confirming there was no joint parliamentary candidate.
According to one senior European official, if the process comes down to a France-Germany clash, the leaders may choose to avoid a crisis and back a Timmermans or Vestager compromise.
"I imagine that a certain number of leaders will try to torpedo a spitzenkandidat, but not all the spitzenkandidaten," the official said on condition of anonymity.
The big three groups are united in opposition to the far-right eurosceptics, but there are signs the Greens, ALDE and the S&D might prefer a progressive candidate over the EPP.
Vestager is a younger choice, has a certain profile as the woman who took on the US internet giants as a regulator and would be the first female president.
But she comes from Denmark – a non-core member which opted out of the euro and the Schengen passport-free zone – and may not have her home government's backing.
Another option might be Michel Barnier, an EPP member and the EU's chief Brexit negotiator, who did not run as a candidate but has been waiting in the wings, ready to step forward.