Jeffrey Donaldson has been declared the new leader of the Democratic Unionist Party after becoming the sole candidate.
The Lagan Valley MP replaces Edwin Poots, who he narrowly lost to in the previous leadership contest last month.
Mr Poots announced his resignation as leader last week following an internal party revolt over his decision to proceed with nominating a new First Minister.
Party chairman Maurice Morrow said he only received one valid nomination for the leadership and so Mr Donaldson was elected unopposed.
In a statement, Mr Donaldson said he has a vision to lead unionism into its second century, to unite Northern Ireland and heal divisions of the past.
He confirmed his commitment to devolution.
Mr Donaldson said: "The Northern Ireland Assembly is the place where every element of our society is represented.
"The coalition government is unwieldy, but it ensures every voice is heard. Such partnership is how we should move forward. It must be based on respect for each other's mandate."
He again stated his intention to call on the British government to take action over the Northern Ireland Protocol.
"I will be speaking with the prime minister at the earliest opportunity to emphasise that it is not realistic to expect stability when every unionist representative in the devolved institutions opposes the Northern Ireland Protocol.
"The government and those who claim to be protectors of peace and stability, must step up and deal with the protocol in a manner which respects the constitutional and economic integrity of the United Kingdom."
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The British government and the EU are locked in a dispute over the implementation of the protocol.
Under the terms of the deal, deliveries of chilled meats - including sausages and burgers - could be effectively banned from crossing the Irish Sea from Great Britain to Northern Ireland at the end of the month.
The UK is considering unilaterally extending the grace period covering sausage shipments, something that Brussels has warned could trigger a retaliation.
But unionists are opposed to the protocol and have repeatedly called for it to be scrapped.
Mr Donaldson said he will play his part but the British government and Europe "must step up and recognise the flaws of the protocol", which he said had been "foisted upon Northern Ireland".
BREAKING: Just over 5 weeks after narrowly losing out to @edwinpootsmla , Lagan Valley MP @J_Donaldson_MP is declared the new leader of the DUP . No-one else applied, so no need for election. @rtenews @LauraHoganTV @RTENewsPaulC @MichealLehane— Vincent Kearney (@vincekearney) June 22, 2021
Earlier, Mr Poots said that he has received a personal assurance from the British government that significant changes will be made to the Northern Ireland Protocol, and predicted there would be a "significant victory" on the protocol in July.
In an interview with the BBC, Mr Poots said he proceeded with the appointment of Paul Givan as First Minister last week, because he believed he could oppose the protocol more effectively with a functioning Assembly.
He said: "My focus is on the Northern Ireland Protocol because that is what makes a constitutional difference to Northern Ireland.
"Yes, I have received assurances that there will be changes to the protocol and that that will be very significant, that the UK government are not going to tolerate how things are and how the EU have conducted themselves since the protocol."
When asked if he had received the assurances personally, Mr Poots said: "Yes."
Meanwhile, Sinn Féin's Conor Murphy has said he hopes that the new DUP leadership moves into a space of honouring agreements and away from "obstructionist" policies.
He said the party had been in turmoil for months and it was a difficult period, but that he hopes that is over now.
"We need genuine power sharing. We need to make sure that agreements made after long and torturous negotiations are actually honoured," he said.
"We are only as good as our word and we have to live up to that when we work in arrangments with each other. I hope the new DUP leadership moves into that space and away from the kind of obstructionist policies adopted here largely over the last year."
In response to a comment today from Mr Donaldson that the protocol had been "foisted" onto the country, Mr Murphy said that it was Brexit that was foisted on Northern Ireland.
"People here democratically voted to stay in the European Union by a significant majority", he said.
Mr Murphy said that this is "beyond nationalism" because people recognise that the European Union is the best position for Northern Ireland to be in.
He said that there are mechanisms to ensure that any issues arising from the protocol can be addressed.
"The DUP needs to engage with that, and the British government needs to genuinely engage with the Europeans," he said.
"There is an opportunity here in this part of the island, where we have one foot in the British markets and one foot in the EU markets".
He warned the DUP over what he called "ratcheting up tension", which he said was "distracting" from the work that needs to be done.
Additional reporting PA