Edwin Poots has resigned as leader of the Democratic Unionist Party after 21 days as leader.
In a statement, Mr Poots said: "I have asked the Party Chairman to commence an electoral process within the Party to allow for a new leader of the Democratic Unionist Party to be elected.
"The Party has asked me to remain in post until my successor is elected.
"This has been a difficult period for the Party and the country and I have 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.”
It means that Mr Poots becomes the shortest serving leader in DUP history.
He was voted in as Arlene Foster's successor on May 14, following a revolt against the former First Minister by supporters of Mr Poots.
He was formally ratified as leader on May 27, meaning he officially served just 21 days in the role.
Sinn Fein issued a statement on Thursday night saying whoever leads the DUP is a matter for the party.
The party says the monumental challenges ahead will requires unity of purpose and urgency concluding that is our focus and should remain the focus of all ministers in the Executive.
It is understood that a planned meeting of the North South Ministerial Council in Armagh on Friday will not now take place.
First Minister Paul Givan, deputy First Minister Michelle O'Neill and Taoiseach Micheal Martin were among ministers from both administrations who were due to attend the event.
Mr Poots planned departure follows a dramatic 24 hours in Northern Irish politics.
Our Political Correspondent Vicki Hawthorne reports
Edwin Poots left a meeting of DUP party officers, amid an internal party revolt over his leadership earlier on Thursday evening.
The DUP leader only said "how are you" to waiting media before been driven off in a waiting car.
Mr Poots declined to respond to media questions about his leadership and whether he faced a motion of no confidence during the meeting.
The remaining DUP party officers left a meeting at their headquarters at 8.50pm, all departing together.
All of them them refused to speak to the media as they left.
A meeting of DUP party officers got under way on Thursday with the recently appointed leader facing a major heave.
Senior DUP figures gathered at party headquarters in Belfast amid speculation Mr Poots could potentially face a vote of no confidence.
The DUP appears to be in internal disarray after a significant majority of its elected representatives opposed the new party leader's decision to nominate a Stormont First Minister. DUP leader Edwin Poots arrived at DUP headquarters for a meeting of the party officers following the party revolt.
He did not speak to waiting reporters on the way in.
A sizeable majority of MLAs and MPs voted against Edwin Poots' decision to reconstitute the powersharing Executive with Sinn Fein in a bruising internal meeting just minutes before the process for nominating Stormont's leaders began downstairs in the chamber of the Northern Ireland Assembly.
The PA news agency understands that Mr Poots and his choice of First Minister, Lagan Valley MLA Paul Givan, had left the room to head for the chamber just before the vote was taken.
One senior party source at the meeting, which happened in the members' dining room, described the atmosphere.
"Dreadful. Utterly dreadful. Never experienced the like of it," said the source.
Earlier on Thursday morning, several DUP MPs and peers sent an urgent email to Mr Poots urging him to hold off nominating Mr Givan until he explained his decision to reassemble the Executive after Sinn Fein secured its key ask on Irish language laws.
Sir Jeffrey Donaldson arrived at DUP Headquarters, speaking to the media only to comment on the "lovely day."
DUP MP Sammy Wilson said that any leader who does not have the support of party officers will "find it very difficult" to stay in their position.
Mr Wilson made the comments as he arrived for a meeting of party officers at the DUP headquarters in Belfast.
Asked if Edwin Poots would survive a vote of no confidence, Mr Wilson said: "It wouldn't be a final decision, it would be decision by the executive.
"I think that any leader who doesn't have the confidence of party officers and didn't have the confidence of their Assembly group and their MPs will find it very difficult to stay in their position.
"You cannot lead people who are not following you. If you have no followers, you can't be a leader, can you?"
Asked if Paul Givan would remain as First Minister of Northern Ireland if Edwin Poots loses the confidence of his party, Mr Wilson added: "Again, that's the issue. If Edwin is no longer leader, then whoever did become leader would have the choice of the First Minister.
"These are all decisions we have got to make.
"The one thing I can tell you is that there is no appetite for a situation where we have an Assembly which can have its powers stripped from it by the Secretary of State at a whim simply because Sinn Fein demand that they get something that they can't persuade others in the Assembly to deliver for them.
"That is no basis to have devolution.
"They wouldn't do it in Scotland, it wouldn't be tolerated in Wales and it shouldn't be tolerated by anybody, not just the DUP, any self-respecting party in Northern Ireland."
A post-midnight announcement by the UK Government committing to pass the stalled laws at Westminster in the autumn, if they are not moved at the Stormont Assembly in the interim, was enough to convince Sinn Fein to drop its threat not to nominate a deputy First Minister as joint head of the devolved Executive.
The development came after a night of intensive talks involving Northern Ireland Secretary Brandon Lewis and DUP and Sinn Fein delegations in Belfast.
Many DUP politicians had warned against a Government intervention on a devolved issues and are furious that Mr Poots was still prepared to enter a new coalition on that basis.
The stand-off between the Executive's two main parties over the thorny language issue has been threatening the future of the fragile institutions in Belfast.
The issue came to a head this week as a result of the process required to reconstitute the Executive following the resignation of Mrs Foster as First Minister.
The joint nature of the office Mrs Foster shared with deputy First Minister Ms O'Neill meant her departure automatically triggered the removal of Ms O'Neill from her position - as one cannot hold post without the other.
While Mr Poots has vowed to implement all outstanding aspects of the 2020 New Decade, New Approach (NDNA) deal that restored powersharing, he has declined to give Sinn Fein a specific assurance that he will move on the language element of the NDNA deal in the current Assembly mandate, a key demand of the republican party.
Amid the dispute, earlier this week Sinn Fein asked the UK Government to step in and move the legislation at Westminster instead. DUP figures had warned Mr Lewis against such a step, characterising it as an overreach into devolution.
However, in the early hours of Thursday, the Secretary of State announced that the Government would table the language legislation at Westminster in October if Stormont had failed to do so by the end of September.
Mr Poots later voiced opposition to legislating on the issue at Westminster but said he would still proceed with nominating Mr Givan as First Minister.
The email subsequently sent to Mr Poots, a copy of which has been seen by PA, was signed by defeated leadership candidate Sir Jeffrey Donaldson, party chairman Lord Morrow, senior MPs Sammy Wilson, Gregory Campbell and Gavin Robinson, former deputy leader Lord Dodds and a number of other senior members.
In total seven of the DUP's eight MPs signed the email, with Ian Paisley being the exception. The party's five peers also signed it.
Many of those who signed the email would have supported Sir Jeffrey in his leadership bid, though some, like MP Paul Girvan, supported Mr Poots's candidacy.