The Government has asked the Chief Justice, Mr Justice Keane, to appoint a constituency commission to review the Irish constituencies in the European Parliament.
With the number of Irish seats in the parliament set to fall to 13 next year from 15, when 10 new member-states join the EU, the Commission will decide which constituencies will lose a seat.
The process will be closely watched by all the parties and by independents, and the outcome of the review could place some MEPs under extreme pressure to maintain their seats.
The Minister for the Environment, Heritage and Local Government, Mr Cullen, has asked Mr Justice Keane to convene the commission to consider the results of the 2002 census and a Central Statistics Office report due next week on "population classified by area".
Mr Cullen wrote to Mr Justice Keane on June 17th asking him to establish the commission as soon as possible.
He said legislation would be required to give effect to the reduction in representation and any other changes in the constituencies that the Commission might seek.
Mr Justice Keane will appoint a High Court judge to chair the commission.
Its members will include the Ombudsman, Ms Emily O'Reilly, the secretary-general of Mr Cullen's Department, Mr Niall Callan, and the clerks of the Dáil and Seanad.
The commission is independent of the Government. However, there is open speculation in political circles that the review of constituencies would see Munster and Leinster or Dublin lose a seat.
In such a scenario, Connacht-Ulster would not lose any of its three seats.
Munster's representation would fall to three seats from four in this case.
Either Leinster or Dublin would lose one of its three seats.