TDs and senators will lose the right to sit on local authorities under a controversial plan set to be brought to Cabinet before Christmas by the Minister for the Environment, Mr Cullen.
In addition, the Minister is to seek approval for the scrapping of plans to have mayors directly elected from 2004 - a key element of his predecessor Mr Noel Dempsey's local government reform package.
In a speech to a number of local authority representative associations yesterday in Malahide, Co Dublin, Mr Cullen said he would "bring clarity quickly to the situation".
Under the package, Oireachtas members will receive approximately €7,500 if they quit their council places quickly so that replacements have time to settle in before the local elections due in mid-2004.
The Minister has been holding regular meetings in recent weeks with members of the Fianna Fáil Parliamentary Party - a majority of whom fiercely opposed change just a month ago.
But Mr Cullen, according to a number of reliable sources, has managed to win a significant level of support amongst Fianna Fáil TDs though senators are still opposed.
It is understood he indicated in discussion that he would offer TDs and senators the right to nominate their successor to councils, though this may have to be achieved by unofficial arrangements.
Senior public representatives are insisting that Oireachtas members must be given the legal right to get information from council officials. "Otherwise, we will get nothing afterwards," one claimed yesterday.
The Cabinet is still divided on the issue, as some ministers believe the abolition of the dual mandate will lead to a loss of Fianna Fáil seats on local authorities.
Fianna Fáil, Fine Gael and Labour representations would be hit by the lack of high-profile candidates.
"This would just open the way for the Greens and Sinn Féin," said one source.
Meanwhile, councillors and local authority staff will have to declare fully their interests under a section of the Local Government Act, 2001 due to come into force within days.
"Local authorities will be advised of the new arrangements in the next few days," Mr Cullen told the General Council of County Councils and the Local Authority Members' Association.