Anti-agreement assembly member Mr Peter Weir tonight won his bid for reinstatement to the Ulster Unionist Party.
Mr Weir who was suspended in February for refusing to follow the Party Whip will be reinstated on July 1.
The move came after a very close vote in the Ulster Unionist Party's 110-member executive meeting in Belfast.
Speaking after the meeting Mr Weir said he was delighted to be back in the party."I think at least today a degree of common sense has prevailed on this issue," he said.
His victory was a boost for the anti-agreement camp ahead of a possible leadership challenge to Mr Trimble at the party's ruling council meeting on Saturday, June 23.
The North Down MLA called on the party to go back to basics in the light of its poor election results last week.
"I would hope that the party would start to shift its position. I will be sticking to the same principles I have always held, no guns - no government and I hope that the party will stick to that," Mr Weir said.
Mr Weir's suspension from the party resulted in him being de-selected as the Ulster Unionist Parliamentary candidate for North Down.
The Assembly member's replacement in the election, Lady Sylvia Hermon, trounced the former MP, anti-agreement UK Unionist leader Mr Robert McCartney in last week's general election.