The Northern Ireland agriculture minister, Edwin Poots, is expected to replace Arlene Foster as leader of the Democratic Unionist party (DUP) after winning swift endorsements to his candidacy. The Stormont assembly member is so far the only candidate to declare and appeared to gain momentum on Friday. Poots, 55, a young Earth creationist who believes the planet is only 6,000 years old, is believed to have been instrumental in the revolt against Foster, who announced on Wednesday she would step down as party leader and Northern Ireland’s first minister. Foster announced on Friday she would also quit as an assembly member and leave the party she has led since 2015. “Politics is a very brutal game,” she told a press conference in her native county, Fermanagh. “I haven’t actually spoken to any of the colleagues who are purported to have signed the letters. They haven’t been in touch. That’s a matter for them. I’ll move on. I’m looking forward to the next chapter as to what I’m going to do with my life.” Her comments underlined the suddenness of the revolt earlier this week, which took the form of letters signed by most of the DUP’s 27 assembly members and reportedly four of its eight Westminster MPs. The party hopes removing Foster will help distance the party from its role in the creation of a post-Brexit Irish Sea border, which has infuriated unionists, who consider it a threat to the region’s position in the UK. The party’s conservative Christian base was also angered when Foster and two DUP ministers abstained on an assembly vote to ban gay conversion practices. DUP moderates hope Sir Jeffrey Donaldson, the MP for Lagan Valley, will join the race. Poots announced his candidacy on Thursday evening, saying he was a proud Northern Ireland man and loved its people. He said: “Northern Ireland is a place that has had many great things over this last hundred years, I wish to see us rebuild, revitalise, reinvigorate and revive for the next hundred.” He said he expected a public campaign, a novelty for a party that has not had a leadership contest since the Rev Ian Paisley founded it 50 years ago. Paisley passed the crown to Peter Robinson in 2008 who then passed it to Foster in 2015. “I look forward to the engagement and the debate with colleagues and the wider public in this contest,” said Poots. Under party rules, an electorate of 41 assembly members, MPs and peers will choose the new leader. Several DUP councillors – who cannot vote – and Christopher Stalford, an assembly member for South Belfast who was initially considered a leadership contender, have endorsed Poots. Bookmakers rated Poots a strong favourite to win. He has taken a hard line on the Northern Ireland protocol that imposed the sea border, which will be the defining issue for the next leader. His view on the Earth’s age prompts scorn. The Free Presbyterian was also criticised for banning gay men from donating blood and opposing gay couples being allowed to adopt children. However, colleagues in the power-sharing executive at Stormont considered him an able, savvy minister.