The DUP has said Mr David Trimble should join with other unionists in removing Sinn Féin from the North's Executive if the British government refuses to do so today.
DUP minister Mr Nigel Dodds said the First Minister must act immediately if Mr Tony Blair or the Northern Secretary, Dr John Reid, did not expel Sinn Féin from government when they deliver their assessment of the Provisional IRA ceasefire to the House of Commons today.
The British government is expected only to warn the Provisional IRA about the consequences of future breaches. Mr Dodds said the Ulster Unionists must not postpone action against Sinn Féin until the autumn.
"We should not wait until September so David Trimble can have his summer holidays. If there is a compelling case to have Sinn Féin/IRA put out of office - and there is -- it should be done as soon as possible and be done on Thursday if the Ulster Unionists will join us," he said.
Anti-agreement Ulster Unionist MP, the Rev Martin Smyth, warned that only "real action" against Sinn Féin would satisfy his party. "Mere words will be insufficient as the government's words have been seen to be empty on too many previous occasions," he said.
Sinn Féin has said it is totally unacceptable that the British government is focusing on the state of the Provisional IRA ceasefire when loyalists have embarked on a "killing spree" of Catholics.
Speaking yesterday after he met Dr Reid to discuss the political and security situation, the Sinn Féin president, Mr Gerry Adams, accused the British government of pandering to unionists.
"The reality is that Catholics are being killed in Belfast. There is a planned, organised campaign by loyalists against Catholics. The unionists' response is to seek the exclusion of Sinn Féin from our rightful place on the Executive. It is disgraceful, it is totally unacceptable."
Mr Adams said he could not understand why loyalists were able to carry out their attacks. "For the life of me, I don't accept for one moment that the police service and the British intelligence agencies didn't have advanced notice that the UDA was about to go on a killing spree."
Mr Adams accused Mr Trimble of failing to defend the Belfast Agreement. He warned that confidence in the agreement was waning in the nationalist community because loyalist violence was being ignored as the focus concentrated on the Provisional IRA.
He said Dr Reid's expected statement at Westminster today on the ceasefire would be "a surreal sideshow" to events on the streets of Belfast. "Those living in the interface areas will find it crazy that the Prime Minister is zeroing in on republicans when they are victims of a loyalist campaign."
The SDLP leader, Mr Mark Durkan, said no one was expecting any moves towards excluding Sinn Féin from government in the House of Commons statement today. He said he thought even Sinn Féin, despite its public statements raising fears, did not believe that was a possibility.
He said he hoped the British government would emphasise the positive work of the Assembly and the other political institutions at Stormont. He warned that it should not threaten to suspend the institutions if there was future paramilitary activity.
The Alliance leader, Mr David Ford, advised the British government to avoid merely giving a definition of what a paramilitary ceasefire should be. Pressure should be applied directly on the paramilitaries to stop all illegal activity, he added.
"The job, not just of the government but of us all, is to create a package of sticks and carrots to encourage them in the right direction," he said.