Over 3,000 Sinn Féin members are expected in Dublin tomorrow for the party's special ardfheis where the party will debate the contentious issue of republican support for the PSNI.
Some 900 delegates who are mandated to vote will be asked to vote on a leadership motion which includes a commitment to support the PSNI and criminal justice system, that the police and criminal justice systems will be fully held to account both democratically and legally and the appointment of party representatives to the policing board and district partnership policing boards.
If passed, the endorsement of the PSNI would be a historic move and is expected to pave the way to powersharing government with the DUP, the Ulster Unionist Party and the SDLP by March.
The party leadership has engaged in an intensive consultation exercise with several meetings held over the past week between grass-root republicans and senior party figures to measure opposition to the policing issue.
Senior officials believe the party's president Gerry Adams will get a clear majority for the party to sign up to the new policing arrangements in Northern Ireland despite some unease in parts of the country.
Republican Sinn Féin (RSF) said they would protest outside the RDS in Dublin as thousands of Sinn Féin members vote on whether to take the unprecedented step to back the Police Service of Northern Ireland.
RSF formed after the divisive Sinn Féin ard fheis in 1986 which saw members agree to abandon the policy of abstentionism and take seats as elected representatives in Dublin and later the Stormont Assembly.
Meanwhile, in her first comments on Police Ombudsman Nuala O'Loan's report into the Royal Ulster Constabulary's Special Branch, President Mary McAleese said the evidence of collusion between police officers and loyalist paramilitaries pointed to the "most despicable" behaviour.
However, the President insisted that the investigation's findings should encourage Sinn Féin to support policing at its conference on Sunday.
Speaking last night at an official engagement at a new centre in London to help Irish emigrants in Britain, Mrs McAleese described Ms O'Loan's report into how Special Branch officers protected a loyalist mass killer in north Belfast as "a deeply disturbing report, a damning report".
"It evidenced the most despicable of behaviour," she said. Asked if a further inquiry into the affair was now necessary, Mrs McAleese said: "I think that it certainly, in the taoiseach's words, does merit follow-up and reassurance, not just to the victims, but to all democrats."
She went on to send a message to Sinn Féin, saying: "I would have thought that in fact that the publication of the O'Loan report should be a tremendous encouragement to those who want to support policing and the rule of law and who are going to promote that argument before the Sinn Féin ard fheis.
"This report should give them the very right kind of information and encouragement to do that."