TAOISEACH Brian Cowen may not have to make a decision on who to appoint as the next EU commissioner until close to the end of the year because of uncertainty over the ratification of the Lisbon treaty.

It had been expected that the new Irish commissioner would be announced in early summer but, with the treaty yet to be ratified in both Ireland and the Czech Republic, it is now thought possible that the current commission may continue on an interim basis until the end of the year, instead of winding up at the end of October.

There are conflicting opinions on this in Brussels, with some EU figures arguing that the EU parliament cannot begin the process of ratifying the new commission until there is legal certainty about the Lisbon treaty. However, others say an interim commission creates other potential legal difficulties.

It is known that both health minister Mary Harney and transport minister Noel Dempsey would be keen on being appointed as the next commissioner.

However, the departure of one of these senior politicians to Brussels would inevitably cause a by-election. In the current political climate, the government would find it impossible to win a by-election, even in Dempsey's Fianna Fáil stronghold of Meath West.

With the government's majority certain to be reduced by two after the Dublin Central and Dublin South by-elections, the Taoiseach may be reluctant to risk a further dilution of government numbers which could leave his coalition vulnerable to a Dáil defeat if a couple of independent TDs or backbenchers voted with the opposition.

While it is also possible that Cowen could appoint somebody from outside the Dáil, there is a body of opinion that he may break with tradition and appoint somebody from the opposition benches. Former minister for finance Ruairí Quinn would be the obvious candidate in this ­scenario.