Steve Aiken is to resign as Ulster Unionist leader, BBC News NI understands.
The South Antrim assembly member has been in charge of the party since November 2019.
However, it is understood frustration with his leadership has been growing across all levels of the party.
Several sources told the BBC there was a “widespread view” that change was needed ahead of next year’s assembly election.
It is understood discussions have been taking place for a number of months about concerns over the party’s recent performance.
One Ulster Unionist source said it was not about a fight for the direction of the party but its entire “existence”.
Below is Aiken’s letter to the party chairman
The last few months have been a momentous time for our Union and for Northern Ireland. It is also a time when Unionism, more than ever, needs positive, hopeful and progressive leadership; leadership which I strongly believe only the Ulster Unionist Party can provide.
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.
I note, with pride, our decision to take the Health portfolio in January 2020 (which all other major parties avoided) and the success that our UUP Health Minister Robin Swann has made in dealing with the CoVID pandemic. When we say in our credo, “Country before Party”, I think we have more than amply demonstrated that point.
However, despite our successes, it has become clear to me that if we are to achieve the breakthrough in the forthcoming Assembly elections, we will need to drive further ahead. To represent the brand of Unionism that builds on hope and not fear, and provides a clear, modern, alternative, that will be both the future of our Party and Northern Ireland will require strong leadership.
Regrettably, however, I believe I have taken our Party as far as it can; to achieve our goals, we now need new leadership. Therefore, after due consideration, I would wish you to accept my resignation as Party Leader, effective from 1000 on the 10 May 2021. I will not be retiring from politics and I will be dedicating myself fully to support our new Party Leader, our Party, but above all to the people of South Antrim.
Finally, may I say what a privilege it has been to lead our Party in these difficult and trying times; while leadership of a political party has many highs and lows, it has been my work with our elected representatives, in particular our MLA team, that has given me the greatest confidence for the future of our great Party.
David McCann holds a PhD in North-South relations from University of Ulster. You can follow him on twitter @dmcbfs