The Taoiseach will tomorrow recommend to EU leaders that they choose Belgium's Prime Minister, Mr Guy Verhofstadt, to succeed Mr Romano Prodi as president of the European Commission.
A senior Irish presidency source told The Irish Times that, when the leaders discuss the appointment over dinner in Brussels tomorrow evening, Mr Ahern would recommend the candidate with most support among member-states.
"The Taoiseach's intention is to make a report. He will be recommending a name to the council," the source said.
The official declined to identify Mr Verhofstadt by name, but sources close to the negotiations confirmed that the Belgian Prime Minister, who is backed by France and Germany, has more support than any other candidate.
The Taoiseach's recommendation will not guarantee that Mr Verhofstadt, who is opposed by Britain's Mr Tony Blair and Italy's Mr Silvio Berlusconi, will secure the post.
The Commission president is chosen by qualified majority, but most leaders would prefer the successor to Mr Prodi to gain consensus backing.
If opposition to Mr Verhofstadt is sufficiently strong, the Taoiseach could be asked to recommend the second most popular choice. This could be embarrassing given that Mr Ahern is himself the second choice.
The Taoiseach this week insisted he had no wish to move to Brussels, although earlier statements suggested that he had not ruled out the possibility.
If all else fails, the leaders may seek to persuade Luxembourg's Prime Minister, Mr Jean-Claude Juncker, to reconsider his pledge to remain in Luxembourg for a further five years.
The Irish presidency source said that the Taoiseach wanted to find agreement on Mr Prodi's successor this week.
In a letter to EU leaders last night, the Taoiseach said he hoped and expected to reach a deal on the constitutional treaty before the end of the two-day summit.
"It is inevitable and natural that every delegation will in the final negotiations continue to argue for its own preferred outcomes. But we must not lose our sense of perspective," Mr Ahern said.
"We have already agreed to maintain the great bulk of the Convention's recommendations, and have reached consensus on most other points."