A PUP Assembly man has warned his party could wreck the Belfast Agreement unless Sinn FΘin does more to win unionist trust.
Mr Ervine made his comments in the wake of disturbances in south Armagh on Sunday evening after police and republican protesters clashed outside British army watchtowers.
Mr Ervine said: "If we walk away from this on the basis that Sinn FΘin are not to be trusted within this process, then we would try as far as it was possible to bring the process down."
With the delicate balance of power at Stormont, the votes of Mr Ervine and his party colleague Mr Billy Hutchinson could prove vital in a future move to oust Mr Trimble. Mr Ervine said the DUP "say they want to pull [the Agreement] down but have never tried, we might not be quite like them." He said there was nothing wrong with peaceful protest but accused Sinn FΘin of orchestrating the violence and engaging in "in-your-face politics" while remaining in government.
"People are going to throw things at me and say loyalists are doing this and loyalists are doing that; I'm not asking loyalists to do anything. Sinn FΘin asked people to come where there was trouble yesterday," he said, referring to the clashes which saw 21 policemen, three soldiers and a number of protesters injured.
The Sinn FΘin Chief Whip said Mr Ervine needed a "reality check" as his comments came on the very day that reports had linked the UVF, to which the PUP is linked, to the recent murder of Mr Ciaran Cummings in Antrim.
Meanwhile, four people from Belfast, including two juveniles, have been charged with riotous behaviour and released on police bail to appear in court later this month.
The four were taken from a bus which was seen leaving the area of the protests, and was later stopped by police on the way to Belfast.