The Ulster Unionist Party seems set to confirm that it will sit down with Sinn Fein at all-party talks on Tuesday. Mr David Trimble is expected to announce the historic move over coming days.
The UUP leader will be demanding Sinn Fein's expulsion from the talks when he takes his seat at Stormont. He is expected to refuse to negotiate with Mr Gerry Adams and to demand that the republican delegation is ejected from the process which it entered only last Monday.
An indictment lodged against Sinn Fein by unionists has been placed on the agenda for Tuesday's talks. It is anticipated that the UUP will be there to argue its case across the table.
The party believes that Sinn Fein should be expelled from negotiations because of the IRA statement last week that it had "problems" with the Mitchell Principles of democracy and non-violence. The UUP will also argue that the IRA was responsible for the bomb which devastated Markethill in Co Armagh.
The IRA has denied responsibility for the attack and both republican and security sources believe that the Continuity IRA, which pledges allegiance to Republican Sinn Fein, was involved.
Mr Trimble has insisted that he will "confront" Sinn Fein but not negotiate with the party. A leading member of the UUP talks team, Mr Jeffrey Donaldson, yesterday said no decision had been taken on tactics for the talks.
"However, we did give a commitment that we would confront Sinn Fein as appropriate and there is no better issue to confront them with than the question of their links with the IRA," he said.
"It is vital that we establish in the talks that the commitment to the Mitchell Principles by republicans commits the IRA to these principles and that any breach by a return to violence will lead to the expulsion of Sinn Fein from the talks."
Speaking at the Northern Ireland Forum yesterday, the DUP leader, the Rev Ian Paisley, said he was "aghast" at the UUP's apparent commitment to enter talks.
He hoped that if the party failed to have Sinn Fein thrown out of negotiations, it would withdraw from the process. An expected meeting between Mr Trimble and Dr Paisley yesterday did not materialise.
Meanwhile, it has emerged that more than £3 million worth of damage was caused to Markethill in Tuesday's bomb attack. Substantial damage was caused to private and commercial property in the town.