Jose Manuel Durao Barroso, the Prime Minister of Portugal, is almost certain to become the next President of the European Commission, after France and Spain made it clear they will not block him over his support for the US-led war in Iraq.

It is expected that Mr Barroso, 48, who began his political career as a Maoist student leader only to become a conservative free-marketeer, will be appointed at a brief summit of EU leaders in Brussels on Tuesday night.

Mr Barroso became a front-runner for the post after Tony Blair helped to block the Franco-German candidate - Belgium's premier, Guy Verhofstadt - at a fractious European summit in Brussels 10 days ago.

But Mr Barroso's support for the US over Iraq had raised hackles in both Paris and Madrid, where the new Socialist government is fiercely critical of American policy in Iraq. Diplomats said yesterday that Bertie Ahern, the Prime Minister of Ireland, which holds the EU presidency, had been assured that France and Spain would not block Mr Barroso.

The Portuguese Prime Minister famously organised a summit in the Azores with President George Bush, Mr Blair and Jose Maria Aznar, the then Spanish Prime Minister who backed the US-led invasion. However, Mr Barroso took a much lower profile than his British and Spanish counterparts and barely appeared in the summit pictures.

He satisfied one key criterion laid down by France: that the next President of the European Commission should come from a country that takes part in all the main EU initiatives, including the euro.

Mr Barroso also comes from the centre-right, meeting a separate demand that the next President should be appointed from the political wing that emerged victorious in the European elections.

If he does get the post, the multilingual lawyer will take on the highest-profile international post ever assumed by a Portuguese citizen. Nevertheless, he will have to work hard to dispel the impression that he emerged as the lowest common denominator. The unassuming Mr Barroso has rarely made an impression so far on the European stage.