The Cabinet has decided to scrap plans to let voters directly elect mayors, despite a last-minute compromise from the Minister for the Environment, Mr Cullen.
Meanwhile, senior Ministers have decided to abolish the right of TDs and senators to sit on local authorities, though they will get €7,500 in compensation if they quit early in the New Year.
In the final draft of his long-awaited proposal, Mr Cullen suggested that mayors could be elected from 2009, rather than from the 2004 deadline laid down by his predecessor in Environment, Mr Dempsey.
The mayoral elections were highly unpopular from the start amongst Fianna Fáil Oireachtas members and others who believed that single-issue candidates could capitalise on voter swings.
During an interview with Radio Kerry on Monday, Mr Cullen said he believed the principle of direct elections was a good one, though he proposed delaying them until the local elections after next.
However, this compromise - which would have given such mayors more powers than were offered by Mr Dempsey - found little favour around the Cabinet table, reliable sources said.
Both issues are set to feature strongly during today's meeting of the Fianna Fáil Parliamentary Party in Leinster House, though most are now resigned to the abolition of the dual mandate.
Last night, a Fianna Fáil TD said: "An awful lot of people regard it as a fait accompli, because the sands have shifted. We have no say in the matter. And there is nothing to be gained from standing out from the crowd on this one, because the public would not forgive you because they see it as double-jobbing, even though Oireachtas members don't get paid for sitting on councils."
A formal announcement of the decision has been delayed until the Minister briefs the parliamentary party in Leinster House. "It should come before the end of the week, if not before," said one source.
The Fianna Fáil National Executive voted overwhelmingly 10 days ago for the abolition of the dual mandate and were equally opposed to the idea of directly elected mayors. However, the Minister has followed through on a promise to backbenchers that they will be able to nominate their successors, though this will be achieved unofficially.
It is understood that the Minister for Health, Mr Martin, and the Minister for Foreign Affairs, Mr Cowen, have accepted the dual mandate ban reluctantly. Both are convinced the decision will threaten Fianna Fáil's number of local authority seats.
