Elliott says he will not put his name forward for position of leader at party meeting this month
The Ulster Unionists are seeking a new leader after the resignation of Tom Elliott.
Once the single biggest party in Northern Ireland, the UUP has been in decline over the past decade and has been eclipsed as the leading force within unionism by the Democratic Unionist party.
Since he was elected UUP leader in 2010, Elliott, a Fermanagh farmer and member of the Orange Order, has been unable to arrest the party's demise.
On Thursday night Elliott said he was aware that some people had not given him a "fair opportunity" to develop and progress many initiatives.
"Some of this obstruction and hostility began immediately following my election as leader and has been relentless since then. However, I accept that is part and parcel of politics."
Elliott added: "The party AGM is scheduled to take place on Saturday 31 March. I have informed the party chairman that I will not be putting my name forward for consideration for the position of leader at that meeting."
At the time of the Good Friday agreement in 1998, the UUP played a pivotal role in bringing a large section of the unionist population to a historic compromise with nationalists and republicans. But since David Trimble won the Nobel peace prize alongside John Hume, the UUP has been shipping votes to the DUP.
The Ulster Unionists were also damaged by the alliance forged by Trimble's successor, Sir Reg Empey, with David Cameron's Conservative party. The joint UUP-Tory platform alienated working-class and Labour-minded unionists, and lost the party's then sole MP at Westminster, Lady Sylvia Hermon.
The UUP is currently divided between those who want the party to exit the five-party coalition government in Belfast and form an official opposition, another faction that wants to remain in power with the other parties and a third that believes there has to be a single unionist party fused with the DUP in the future.