Edwin Poots has been elected as the new leader of the Democratic Unionist Party.
Stormont Agriculture Minister Mr Poots was vying with the party’s Westminster leader Sir Jeffrey Donaldson to replace Arlene Foster, who announced her resignation last month.
The Lagan Valley MLA won by a razor-thin 19 votes to 17 in the poll carried out within the party’s 36-strong electoral college.
It was the first contested leadership vote in the DUP’s 50-year history.
In his acceptance speech, Mr Poots, who recently underwent cancer surgery, pledged that the DUP would be the “authentic voice” for unionism under his leadership.
“It is an immense honour and pleasure to stand here today in this position, it is not a position that I expected to be in some weeks ago,” he said in an address at party headquarters in east Belfast.
“However, things can change quite radically.” Mr Poots added: “I’m looking forward to a positive relationship right across Northern Ireland with my party colleagues and indeed with people from other parties.
Mr Poots praised the “resilience” of Northern Ireland people through the first 100 years of its existence.
“It’s that resilience that we are going to go forward (with) and make Northern Ireland a good place,” he said in an address at party headquarters in east Belfast.
“My father was a founder member of the DUP some 50 years ago, and I joined after the death of the Reverend Robert Bradford MP in 1981 and throughout all of that period this party has been the authentic voice of unionism and will continue to be the authentic voice of unionism under my leadership.”
Mr Poots says he will continue to campaign against the Northern Ireland protocol as DUP leader.
Sinn Féin leader Mary Lou McDonald wished Mr Poots well and said the work must now begin to deal with the challenges that lie ahead.
Ms McDonald said the Executive must move ahead with the same unity of purpose and ambition that has been seen over the past year in the fight against Covid-19.
"We need to build the economy and get people back to work, support the health service and meet the challenge of reducing waiting lists, deliver ambitious housing plans and we must deliver on agreements which bring about the political change and social reform the public rightly expect and require," said Ms McDonald.
"The incoming leader of the DUP faces a new political landscape in the north, across the island and indeed between our two islands.
She said Sinn Féin wants power sharing to work and the party is strongly committed to making their political institutions work so that they can create a better and more equal society for all.
Taoiseach Micheál Martin congratulated the new DUP leader and said his door is always open and that he looks forward to engaging with Mr Poots.
"His appointment comes at a critical time when it is ever more important for us to work together to keep the peace process firmly on track and to promote prosperity on both a North/South and East/West basis,” said Mr Martin.
"I wish Edwin every success in his new role and look forward to working closely with him, and all of the parties in Northern Ireland, to support peace, stability and progress in Northern Ireland and the Institutions of the Good Friday Agreement."
Foreign Affairs Minister Simon Coveney also congratulated Mr Poots and said looks forward to engaging and working with him.
British Prime Minister Boris Johnson said he looks forward to working with Mr Poots, Brandon Lewis and the wider Executive "as we build back stronger for the people of Northern Ireland".
Mrs Foster was ousted after an internal heave by party colleagues unhappy with her leadership and will step down from that role on May 28, and as Stormont First Minister at the end of June.
Outgoing Ulster Unionist leader Steve Aiken has congratulated Edwin Poots on being elected DUP leader, but said his “fingerprints are all over the Northern Ireland Protocol”.
He said: “I would wish to extend our congratulations to Edwin Poots on being elected DUP leader and to Paula Bradley as deputy leader.
“Edwin may try to signal his election as a new era for the DUP following Arlene’s resignation, but no matter what way you look at it, his fingerprints are all over the Northern Ireland Protocol.
“If the new DUP leader wishes to present the image of a ‘new’ approach, he owes us all an explanation as to how his party’s squandering of their transient period of influence has resulted in the damaging position we now find ourselves in.
“Regrettably, the so-called stewardship of the Union in the DUP’s hands has been an abject failure – not just for Unionism but for all the people of Northern Ireland.”