Edwin Poots has been elected leader of the Democratic Unionist party (DUP) on the promise of remoulding Northern Ireland’s biggest party and ratcheting up opposition to the Irish Sea border. On Friday the Stormont agriculture minister narrowly beat Sir Jeffrey Donaldson, a DUP MP, in a two-horse race to succeed Arlene Foster. He won by 19 votes to 17 from an electorate comprised of the DUP’s eight Westminster MPs and 28 Stormont assembly members. The tight margin reflected deep division about the party’s direction and may complicate Poots’s efforts to stamp his authority. Poots, 55, is a young Earth creationist from the party’s conservative Christian wing who believes the planet is 6,000 years old, a belief that could impede the party’s effort to court new voters. However, Paula Bradley, 51, the party’s most socially liberal assembly member, was elected deputy leader, beating the party’s veteran Westminster MP Gregory Campbell by two votes. Bradley said she would be a “critical friend” to the new leader. With Donaldson and Campbell associated with the old guard, the results suggested a party keen for a new direction and not a return to its Free Presbyterian Paisleyite roots. “Today my colleagues have bestowed upon me the greatest honour of my life,” Poots beamed in a video message posted on Twitter minutes after the official party announcement. He thanked God for his health – he was recently treated for cancer – and family and friends for their support. He said he was taking an important role at a pivotal moment in Northern Ireland’s history. In a statement to the media at Stormont, Poots said he would meet Brandon Lewis, the Northern Ireland secretary, in Belfast next week over Brexit’s contentious Northern Ireland protocol. He also said he intends to be in London later in the week to continue those discussions with the government. Poots urged fellow unionists to work with him to oppose the protocol, which has placed new economic barriers between the region and the rest of the UK. “I want to say this very clearly: I will be a leader in unionism who’ll be reaching out to other leaders in unionism,” he said. “I want to see unionism working together. “The Northern Ireland protocol is proving to be a massive challenge for us and if we are to fight this to ensure that everybody in Northern Ireland is not worse off as a consequence of the protocol, then it’s for us to do that together.” Poots said he would appoint a party colleague as first minister so that he could focus on restructuring the DUP while remaining agriculture minister. His victory comes at a moment of flux. Loyalists have vowed to escalate protests against the Northern Ireland protocol during the traditional summer marching season. The Ulster Unionist party is in the process of choosing a new leader. Sinn Féin is pushing for a unification referendum. And some analysts predict that strains in Stormont’s power-sharing institutions will trigger early assembly elections. The first leadership contest in the DUP’s 50-year history followed a revolt against Foster, who was blamed for the post-Brexit Irish Sea border, excessive control by unelected officials and a perceived softening of the party’s opposition to same-sex marriage. Campaigning took place behind closed doors and in private phone calls. The focus on internal reforms and opposition to the protocol, with Poots and Donaldson talking up resistance, gave the contest an air of “unrealism” since the DUP could not bin the protocol, said Jonathan Tonge, a University of Liverpool politics professor, who is an authority on the DUP. Within Stormont, Poots is viewed as a pragmatist who has negotiated deals with Sinn Féin and the Irish government and who could sell a compromise on the protocol to DUP hardliners. London and Dublin will wait to see if he ceases cooperation with the Irish government or impedes checks on goods coming from Great Britain, acts that could trigger a wider political crisis. Boris Johnson tweeted his congratulations to Poots upon confirmation of the result, saying: “People across the UK are best served when we work together, & I look forward to working with him, Brandon Lewis [Northern Ireland secretary] & the wider executive as we build back stronger for the people of Northern Ireland.” The Irish taoiseach, Micheál Martin, also extended his congratulations, and said his door is always open to the DUP’s new leader. The party’s focus on internal structures and purging Foster’s lieutenants overlooked the bigger challenge of stemming a haemorrhage of voters, said Tonge. “All that stuff is fiddling while unionism burns because what really matters is the DUP appealing to a wide section of unionism.”