Edwin Poots has resigned as leader of DUP after just 21 days in the job.
It came after he agreed a deal with Sinn Fein and the Westminster government to ensure Paul Givan became Northern Ireland’s first minister.
A majority of DUP members in the assembly wanted to delay the process and he faced an internal revolt at a party meeting.
Mr Poots, who took over from Arlene Foster in May, narrowly defeated Sir Jeffrey Donaldson in a leadership vote.
Earlier on Thursday, Paul Givan was nominated as the new first minister at Stormont while Sinn Féin’s Michelle O’Neill returned as deputy first minister.
The BBC understands a motion of no confidence was mentioned but not tabled at the meeting of DUP officers.
Party sources described the meeting as “robust” and said it had become clear Mr Poots knew he had to resign.
It is thought the process to appoint his successor could move “at pace”, according to one DUP figure.