“Mr Juncker did not stand anywhere and was not elected by anyone.”

So says David Cameron in an article published in several European newspapers on Friday, making his strongest public intervention yet to stop Jean-Claude Juncker from becoming the next European Commission President.

Considering him too federalist, the British premier is seeking to create an anti-Juncker front but Germany’s Chancellor Angela Merkel has publicly supported Luxembourg’s former leader.

Juncker is frontrunner because his centre-right European People’s Party came out on top in last month’s EU elections.

Cameron’s efforts to change Merkel’s mind have been hindered by the entry of one of her rivals – Germany’s anti-euro AfD party – into his European political family, despite his attempts to stop this.

“The prime minister made his views very clear to us,” said Syed Kamall, leader of the European Conservatives and Reformists group.

“He asked me as leader of the British Conservatives to make it clear that he wished Conservative MEPs not to vote for AfD in the vote. But we are only one part of an ever growing group.”

EU leaders are set to decide on their candidate for the Commission Presidency in a summit at the end of the month. The name must then be presented to the European parliament for approval.