Jean-Claude Juncker's bid to become European Commission president appeared to receive a boost on Tuesday, ahead of the EU leaders' summit where heads of state would discuss Sunday's election and possible candidates to replace Jose Manuel Barroso.

Leaders of the major party alliances at the European Parliament said they thought the first chance at drumming up support as Commission president should go to Juncker, whose European People's Party (EPP) alliance was the strongest single performer in the European Parliament elections.

The president of the center left Progressive Alliance of Socialists and Democrats (S+D), Hannes Swoboda, said the outgoing party presidents would ask European heads of state "to give Jean-Claude Juncker - the candidate from the largest political group in the European Parliament - a clear mandate to start negotiations with other political groups."

However, Swoboda also said that his alliance would only support Juncker after these negotiations if his program "meets the needs and concerns of EU citizens."

Swoboda's S+D had put forward German Social Democrat Martin Schulz as its lead candidate for the presidency. The alliance finished as the second power in the European Parliament after the EPP, with 186 seats to the conservatives' 212. Neither bloc is even close to a working majority in the 751-seat parliament.

Parliamentary approval just the one hurdle

Juncker's candidacy for the presidency is particularly unpopular with a fellow center-right politician, Britain's Conservative prime minister, David Cameron. Britain's Conservatives are not in the EPP, despite being the UK's traditional major center-right party, instead chairing a rival alliance, the European Conservatives and Reformists.

Juncker, the longstanding Luxembourg prime minister who also helped guide eurozone economic policy during the bloc's sovereign debt difficulties, is considered a Brussels insider and committed federalist - positions that conflict with Cameron's repeated calls for European reform.

British voters were among those siding with anti-establishment parties at the polls last week, with the explicitly euroskeptic and anti-immigration United Kingdom Independence Party (UKIP) emerging as the strongest single British faction at the European Parliament. Cameron's Conservatives came in third, also behind the main opposition Labour Party.

In France, the far-right National Front party of Marine le Pen was the best-supported party, ahead of the conservative opposition UMP and then the Socialists of President Francois Hollande. Hollande has since called for reform in Europe, albeit focusing on different changes to those endorsed by Cameron.

Any future European Commission president will require approval from both the European Parliament and the EU's heads of state. Both Angela Merkel and David Cameron have said that the process of picking a president will likely take time, saying an immediate nomination at Tuesday's summit in Brussels is unlikely.

msh/kms (dpa, Reuters)