Doug Beattie has announced his resignation as Ulster Unionist Party leader.
There has been internal tensions over his role in recent weeks.
Mr Beattie cited “irreconcilable differences” between himself and party officers “combined with the inability to influence and shape the party going forward” as reasons for his decision.
The Upper Bann MLA took over as leader of the party in May 2021. The party has had three leaders, including Mr Beattie, in total, since the resignation of current Health Minister Mike Nesbitt after the 2017 Assembly election.
The party regained a seat at Westminster in the general election in July. It followed recent difficult electoral performances for the party.
It’s thought the tensions are linked to the selection of Colin Crawford as the party’s new North Antrim MLA, replacing Robin Swann who became MP for South Antrim.
In a statement on Monday morning, Mr Beattie said it has been a “huge honour” to serve as UUP leader and noted the party’s return to the green benches at Westminster and having Tom Elliott enter the House of Lords.
Mr Beattie said his job has “not been easy “ and at times has been “both lonely and isolating”.
“I am no stranger to leadership and that is how it often feels in taking a toll both physically and mentally. It also strains friendships and political relationships,” he added.
“It is now clear that some believe the momentum needed to keep the Ulster Unionist Party moving in the right direction cannot come from me.
“Irreconcilable differences between myself and party officers combined with the inability to influence and shape the party going forward means that I can no longer remain the party leader.
“Therefore, I shall stand down as the party leader and allow the party to immediately begin the process to select a new leader who may maintain the confidence of the party and continue the momentum I have started.
“It is important to acknowledge the loyalty and support from many within the party. This includes the MLA group and many other elected and non-elected members.”
Mr Beattie acknowledged that some within the party did not agree with his vision and the direction he set the party on, but he hopes “they can see that in the long term only an inclusive Ulster Unionist Party, promoting a positive message, can secure our future”.
He added: “I hope the new leader is given the freedom to act.”
Earlier this year there was anger from some within the party over the decision to nominate Robin Swann as Stormont Health Minister at a time when he was campaigning for the Westminster seat.
Lagan Valley MLA Robbie Butler is the party’s deputy leader. Before Mr Swann was nominated for an Executive post, Mr Butler was widely tipped to become education minister.
Mr Beattie initially saw success when he took over as leader, with the party overtaking the DUP for a short period in opinion polls.
The UUP leader’s background is in the military and he served three tours in Afghanistan.
He was later awarded the Military Cross, which is the third-highest award for gallantry in the face of the enemy.
Mr Beattie retired from the army before joining the UUP and being elected as a councillor in 2014.
He later won a seat in Upper Bann in the Assembly election in 2016.