The leader of Northern Ireland’s biggest political party has agreed to step down, just three weeks after taking up the post, a dramatic culmination to a row over how to continue the region’s power-sharing government.

Edwin Poots announced his resignation as Democratic Unionist party leader in an emailed statement after a four-hour meeting with DUP officers in Belfast. He will remain in office until his successor is appointed.

The creationist, who was swept to power promising to be tougher on fundamental unionist issues, had been expected to face a vote of no confidence after defying the party and in effect agreeing concessions with the nationalist party Sinn Féin to save the power-sharing government from collapse.

“This has been a difficult period for the party and the country,” Poots said in his resignation statement, adding that he had “conveyed to the chairman my determination to do everything I can to ensure both unionism and Northern Ireland is able to move forward to a stronger place”.

Earlier on Thursday, Poots had defied a DUP vote and nominated Paul Givan as Northern Ireland’s new first minister, enabling the continuation of Stormont’s power-sharing government with Sinn Féin, which had convinced Westminster to fast-track legislation advancing the Irish language.

DUP members objected to both the principle of London’s intervention and the fact that Sinn Féin had won a concession.

The revolt against Poots is the latest sign of turbulence in Northern Ireland that has been fuelled by the terms of the UK’s Brexit deal with the EU.

Sammy Wilson, a senior DUP MP, publicly criticised Poots’s nomination of Givan on Thursday afternoon and had refused to rule out a vote of no confidence in his leadership.

“The numbers are worse than they were against Arlene [Foster],” one person familiar with the situation had said before the meeting with party officers, referring to the ousting of Poots’s predecessor in April after she lost the support of DUP politicians.

Sinn Féin had stated that it would continue in the administration only if legislation to enhance the status of the Irish language were quickly approved at Stormont.

The DUP had refused, but the deadlock was broken on Wednesday night when the UK government indicated it would pass the legislation at Westminster.

The move had cleared the way for Poots to nominate Givan as Foster’s successor as Northern Ireland first minister. Sinn Féin renominated Michelle O’Neill as deputy first minister.

But Wilson said DUP MPs and the party’s members at Stormont had made it “very, very clear” in a vote earlier on Thursday that they were against Poots’s immediately nominating Givan.

“It’s difficult to have confidence in anyone who sets aside the strongly held views from all the various sections of the party and goes ahead,” added Wilson, referring to Poots.

“I guarantee that most unionist people . . . will be appalled that the powers of the assembly will . . . be set aside to promote a niche interest of Sinn Féin.”

Poots had said he was putting forward Givan without “a precondition from Sinn Féin” and the objective was to make Northern Ireland “a better place for everyone”.

Sinn Féin leader Mary Lou McDonald said on Wednesday she had asked Westminster to intervene because it had become “abundantly clear” that the DUP would not prioritise the Irish language legislation.

Poots was DUP leader for less than three weeks, taking over from Foster after Brexit played an important part in her ousting as DUP leader and first minister.

Deirdre Heenan, professor of social policy at Ulster University, earlier said it was “hard to overstate the strategic political and strategic failure of the Poots putsch”.

“That DUP [members at Stormont] and MPs voted against nominating for first minister reflects anger and disarray within the party,” she added.