Outgoing Ulster Unionist leader Steve Aiken has formally resigned as party leader, stating he was "aware of his limitations".
In a press conference in the Great Hall at Stormont, Mr Aiken was flanked by party chairman Danny Kennedy as well as MLAs Doug Beattie and Robbie Butler, the two men who have been tipped to replace him.
Former submarine commander Mr Aiken said: "I have taken this difficult decision because, more than ever, unionism and those in Northern Ireland who believe in the union need a clear political voice."
He said the UUP had delivered for the people of Northern Ireland but added: "I am, however, self-aware enough to realise that our party, despite our strengths, is not breaking through - I am also very aware of my limitations and despite successes over the past 19 months, I realise that a change in leadership is needed."
Mr Aiken has said he will stay in position until a successor is found.
Continuing his statement, Mr Aiken said there was a place for a "strong, progressive and inclusive" unionist party in Northern Ireland.
He added: "That party is the Ulster Unionist Party. Our party has delivered for the people of Northern Ireland for many years and in the centenary of Northern Ireland continues to do what is right - not just for unionists, but for everyone.
"If anyone doubts our credo of country over party look at how we took the health portfolio when all others avoided it - and I think we are all glad of not just our excellent health professionals, but also for the inspired leadership of Robin Swann."
The South Antrim MLA added: "Having been in many command positions before, I know and recognise the critical point when a change is needed - for the greater good and for a reinvigoration of the fight - and that time is now."
MLA Robbie Butler refused to be drawn on whether he intended to run for party leader but instead paid tribute to the leadership of Mr Aiken.
Party colleague Doug Beattie said there had been "much speculation" that he would enter the contest to become the new Ulster Unionist leader.
He added: "I will think about whether it would be right for me to stand. I will take soundings if the party want me to be leader, and if they want to be led by me, and I will make a decision."
UUP chairman Danny Kennedy said the change in leadership in the party would not be carried out in the same way as the DUP.
He said: "Not for us the nastiness of leadership changes carried out in dark corners like the DUP removing Arlene Foster, who frankly was deserving of better.
"Nor indeed replicating what Sinn Féin did in their purge in Foyle."
