Brussels must focus on finding an "honest and trusted broker" for the European Union's top job and reject attempts of a "backdoor power-grab" aimed at installing Jean-Claude Juncker in the post, David Cameron has warned.
In a direct appeal to Europeans, the Prime Minister lashed out over the behind- the-scenes deal that has seen the arch-federalist pushed forward as the front-runner for the presidency of the European Commission.
Mr Cameron said the former Luxembourg premier " did not stand anywhere and was not elected by anyone" and most voters had been completely unaware that he was in the frame for the powerful position when they went to the polls last month.
In an article that has been circulated among the European press, Mr Cameron wrote: " We must focus on finding the best candidate for Commission President. Someone who can deliver reform, driving growth and creating jobs, and accepting that Europe's needs may best be served by action at the national level. An honest and trusted broker able to re-engage Europe's voters."
The Prime Minister is vehemently opposed to Mr Juncker's bid to replace Jose Manuel Barroso, who steps down in the autumn after 10 years in the role.
His opposition is backed by Deputy Prime Minister Nick Clegg and Labour leader Ed Miliband but has seen Mr Cameron clash with German Chancellor Angela Merkel, who has publicly supported the candidacy.
Mr Juncker has been put forward by the centre-right European People's Party - the largest grouping in the European Parliament following last month's elections - but is regarded in London as an opponent of reform, whose appointment would make UK departure from the 28-nation bloc more likely.
Under the Lisbon Treaty, the European Council - made up of the leaders of the member states - is supposed to "take into account the elections to the European Parliament" in choosing a candidate for the presidency - who must then be approved in a vote of MEPs.
But Mr Cameron claimed that MEPs have " invented a new process" by selecting lead candidates, known as Spitzenkandidaten, for each grouping of parties in the parliament and then pushing forward the one from the largest bloc.
The "backroom deal" was never agreed by the European Council or ratified by national parliaments and would set a dangerous precedent, he warned.
Mr Cameron wrote: "S upporters of Spitzenkandidaten argue that the elections have happened, the people of Europe have chosen Jean-Claude Juncker as Commission President and that it would be undemocratic for elected national leaders to choose anyone else.
" It is not an attack on Mr Juncker, an experienced European politician, to say this is nonsense. Most Europeans did not vote in the European Parliament elections. Turnout declined in the majority of member states.
"Nowhere was Mr Juncker on the ballot paper. Even in Germany, where the concept of Spitzenkandidaten got the most airtime, only 15% of voters even knew he was a candidate. He did not visit some member states.
"Those who voted did so to choose their MEP, not the Commission President. Mr Juncker did not stand anywhere and was not elected by anyone.
" To accept such a claim would be deeply damaging for Europe and would undermine, rather than strengthen, the EU's democratic legitimacy.
" It would shift power from national governments to the European Parliament without voters' approval. It would, in reality, prevent a serving prime minister or president from ever leading the European Commission - artificially restricting the pool of talent precisely when the EU needs to find the very best."