FILE PHOTO: Manfred Weber, chairman of the European People Party (EPP), takes part in a summit of the party in St Julian's, Malta, March 30, 2017. REUTERS/Darrin Zammit Lupi/File Photo

BRUSSELS (Reuters) - German conservative Manfred Weber will announce his candidacy on Wednesday to front the center-right in European elections next May, a source familiar with the plans told Reuters.

The Bavarian leads the center-right European People’s Party caucus, a grouping of conservative parties in the European Parliament. If other member parties give him their backing, Weber would be among the frontrunners to succeed Jean-Claude Juncker as European Commission president a year from now.

The EPP, the biggest group in the European Parliament and whose parliamentary group Weber will address in Brussels on Wednesday morning, will choose its lead candidate at a convention in Helsinki in November. Michel Barnier, the French former foreign minister who is now running the EU’s Brexit talks with Britain, and former Finnish prime minister Alexander Stubb are also possible contenders but have yet to declare themselves.

Other parties are not expected to name their top candidates until later in the year or early in 2019.

Juncker’s successor must be agreed by leaders of European Union member states following the European elections in May that will see anti-EU parties bidding to increase their minority in the legislature. The parliament, which must approve the leaders’ nominee, will push them to choose a Commission president from among the lead candidates of the main parties - despite many leaders insisting they should be free to nominate anyone.

At 46, Weber is relatively young and has held none of the high ministerial offices or national leadership roles typical of past heads of the EU executive. However, parliamentary leaders argue that naming a Commission president from among those elected to the European Parliament would help rebut arguments that the European Union is bureaucratic and authoritarian.

Weber has secured the backing of his own party, the Bavarian Christian Social Union, which is closely allied to German Chancellor Angela Merkel’s Christian Democrats, the CDU. His declarations in public tend to confirm reports that Merkel has given Weber her personal endorsement ahead of a CDU meeting on the issue of the EPP candidate next week.