Sinn FEin delegates to the party's resumed ardfheis on May 10th are expected to be asked to amend the organisation's constitution to allow members to take their seats in the new Northern Assembly.
A motion requesting an end to the party's constraint on taking seats in a "partitionist" institution is likely to be tabled by Sinn Fein's ardchomhairle, which will determine its position in advance.
A two-thirds majority of delegates is required to change the rule dating from the 1920s but republican sources last night thought the required support exists to drop the ban on Sunday week.
The development indicates the leadership's keen determination to participate in the 108-seat assembly and is seen as further evidence of its endorsement, in both jurisdictions, of the Belfast Agreement. The assembly elections take place on June 26th.
Sinn Fein changed its abstentionist policy on participation in local government at council level in Northern Ireland in 1983. Three years later it ended its abstentionist policy on taking seats in the Dail, a move that precipitated the split with Republican Sinn Fein. However, the party's ban on taking seats at Westminster will continue.
"We cannot remain abstentionist as regards either assembly in Ireland," one republican source said. "If we did, Sinn Fein would only win five or six seats in the forthcoming assembly elections. If it is changed, however, we should get about 20 seats".
Retaining the ban on joining the assembly would make Sinn Fein look "silly" and "does not cost us one iota of principle", the source added.
Senior party members indicated to delegates at the ardfheis on April 19th that they should support involvement in the assembly.
The ardfheis will also vote on how to approach the May referendum on the agreement. The party president, Mr Gerry Adams, will open the debate and indicate the ardchomhairle's recommendation on whether or not to support it. Only a simple majority is required.
Party sources said considerable unease existed among republicans, particularly in the Republic, about the proposals to change Articles 2 and 3. The insertion of a consent clause in Article 3, to prevent any change in Northern Ireland's status unless the majority of people living there wanted it, was giving rise to deep unease.
Mr Adams and Mr Martin McGuinness have said that while the agreement was not a settlement, it contained the basis for advancement.
Blair and Adams hold "constructive" meeting; More EU funds expected; Dail parties expected to adopt joint approach; UUP criticises anti-agreement campaign: page 6