Michael McGrath set to be nominated as Ireland's next European ...

The nomination of Mr McGrath comes as Taoiseach Simon Harris prepares for a meeting of the European Council later this week during which a number of key European jobs will be divvied up. 

It is understood that Mr Harris was keen to receive a nominee this week before the political horse-trading begins amid speculation that Ireland has designs on an economic unit of the European Commission. 

Ireland's current commissioner Mairead McGuinness currently holds the directorate general of Financial services, financial stability and Capital Markets Union.

It is not yet clear whether Mr McGrath's nomination would see him depart Cabinet now or when the Commission begins its term at the end of October. Should it be the former, it will spark something of a mini-reshuffle in the Fianna Fáil ranks in government. 

Mr McGrath's departure would leave one open seat at the Cabinet table with new Fianna Fáil deputy leader Jack Chambers and former Agriculture Minister Dara Calleary among those touted as possible replacements for Mr McGrath, though it is felt that Mr Martin would be more likely to move either Norma Foley or Darragh O'Brien to the Finance portfolio and put the new addition in their vacated role, given its seniority.

However, some Cabinet sources questioned whether taking Mr O'Brien out of his Housing portfolio would be a good idea, given the focus the Government has placed on it and whether changing ministers would "send the wrong message" to the electorate.

In the event that Mr McGrath remains in place, he would oversee the delivery of the Budget in October or late September before his departure, which some in government say would mean an election shortly after. 

One senior source said that there would be "no point" reshuffling the Cabinet for the last four months of its lifetime and that going to the polls in early November could make sense for the Government.

Within Fianna Fáil, there is some trepidation at letting Mr McGrath leave for the €310,000 a year job in Brussels. 

Some see the decision as removing one of the party's strongest and most popular performers from the domestic stage in the run up to a general election, while others believe that it clears the way for newly-installed deputy leader Jack Chambers to become Micheál Martin's heir apparent.

However, the domestic ramifications of the move are less complex for the party. In the event of a Cork South-Central by-election, Fianna Fáil would be odds-on to retain the seat, given the success of Mr McGrath's brother Seamus in the recent local elections. 

The Carrigaline councillor took two-and-a-half times the quota, with his surplus helping to bring his party colleague Audrey Buckley in on the fourth count.

Speaking in Brussels on Monday, Tánaiste Micheál Martin said that the most important thing about Ireland's nominee was the "high-calibre" of who is sent.

Speaking last week, Taoiseach Simon Harris said that what "is really important that we send the best people to represent us in Europe, and there are many people who would make fine commissioners".

"Most importantly, though, is to know the identity of that person pretty quickly in the next short period of time, so that then we can begin the process of engaging with the new President of the Commission on what role or portfolio might be best for them, for Ireland and for them and Ireland making impact in Europe."