Former Eurogroup chief Jean-Claude Juncker is emerging as the top candidate for the centre-right European People's Party in the upcoming EU elections, amid positive signals from Berlin.

German newspaper Welt am Sonntag on Sunday (2 February) reported that Chancellor Angela Merkel has given her backing to the former Luxembourg Prime Minister and long-time EU figure.

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Merkel and Juncker have had their ups and downs (Photo: President of the European Council)

This is contrary to previous reports suggesting she would favour a different candidate.

Juncker headed the eurogroup of finance ministers from its inception in 2004 until 2013 and was the longest serving prime minister in Europe until last December, when a new government was formed in Luxembourg.

A source within the European People's Party told this website on Monday that Merkel never "really rejected" Juncker.

"He is the frontrunner, he poses no problem to Merkel in the runup to the EU elections. The question is, will she back him afterwards," the source said.

A spokeswoman for Merkel told this website on Monday that the chancellor "sticks to the agreed calendar" - meaning that the official top candidate for the EPP will be announced in March at a party congress in Dublin.

"Until then, the chancellor will not engage in any speculations about the personnel," the spokeswoman said.

But even if Juncker secures the EPP nomination in March, there is no guarantee that he will get the job.

In a twist of irony, Juncker may fall victim to the very "secret, dark debates" he once said he favours for reaching deals on sensitive EU matters.

Merkel, unlike other EU politicians who want to use a novelty in the Lisbon Treaty allowing parties to put forward lead candidates for the EU commission, has already suggested there will be no automaticity for the candidate of the winning party to become head of the EU executive.

In previous years, the head of the EU commission was always selected as part of a package deal with the EU council chief and the foreign affairs tsar. The heads of Nato and the European Parliament also play a role in the overall deal, which has to take into account gender, geography and political colour.

Prime Ministers who are potential candidates - Ireland's Enda Kenny or Poland's Donald Tusk - have so far ruled out being interested in the job. But this is thought to be because it would leave them as lame-duck-leaders back home. And in the event the EPP does not emerge as winner in the EU elections, the lead candidate will go home empty-handed.

Another potential problem for Juncker is the fact that he is not an MEP and has also ruled out running for the European Parliament.

Almost all other parties have put forward MEPs as lead candidates: European Parliament chief Martin Schulz for the Social Democrats, former Belgian PM Guy Verhofstadt for the Liberals, France's antiglobalisation fighter Jose Bove and a young German MEP - Ska Keller - for the Greens.

Only the leftist group has put forward a politician who has not served in the European Parliament: Greek opposition leader Alexis Tsipras.