Ulster Unionist leader Sir Reg Empey has said "elements in the government" are opposed to his assembly deal with PUP leader David Ervine.
Sir Reg Empey says "elements in the government" oppose the deal
Sir Reg has said Mr Ervine joining the UUP assembly team will cost Sinn Fein a ministerial seat in any executive.
He has confirmed his party has been in touch with other assembly members about increasing the strength of the Ulster Unionist group.
However, he has refused to identify which politicians had been involved.
Mr Empey made the comments on the BBC's Inside Politics programme on Saturday.
The UUP has said Mr Ervine's move would pass a third Sinn Fein executive place to them and see a unionist majority for the first time on the executive.
Earlier this week, DUP leader Ian Paisley said by linking with the PUP the UUP were "allying" themselves with terrorism.
The party's deputy leader Peter Robinson said the Ulster Volunteer Force - with which the PUP has links - was active in criminal and paramilitary areas, according to the latest report by the Independent Monitoring Commission.
However, Mr Ervine has said a stronger unionist presence on any executive that was formed, would bolster confidence in his community.
"I think I'm doing a very logical, shrewd political move," he said.