Ukip leader Henry Bolton is fighting to keep his job after he lost a no confidence vote at a meeting of senior officials.
Party members will now decide his fate in a vote at an emergency meeting in February.
Mr Bolton has been under intense pressure to quit after his now former partner Jo Marney was revealed to have made highly offensive comments about Meghan Markle and black people.
But he insists the party cannot afford another leadership election and warned the result of the no confidence vote will lead to fresh in-fighting that could finish off the party.
Ukip's national executive committee unanimously backed a vote of no confidence in Mr Bolton after he put his case to members for remaining in post.
A Ukip spokesman said: "The committee took the decision to hold a vote of no confidence in the leadership of Henry Bolton.
"The vote was carried unanimously with the exception of the leader.
"This decision will automatically trigger an emergency general meeting of the party, to allow the membership of Ukip the democratic opportunity to decide to endorse or reject that vote of no confidence."
Under Ukip rules, an emergency general meeting must be staged within 28 days.
Members will be told about when and where it will be held in the next 10 days.
Mr Bolton said a contest to replace him "would be financially almost unviable for the party".
The under-fire leader said previously his "romantic" relationship with 25-year-old model Ms Marney was over but he admitted they were "still in touch" after pictures emerged of them meeting up.
He left wife Tatiana, 42, who gave birth to their second daughter at London's St Pancras station in 2016 after going into labour on a train, prior to his relationship with Ms Marney becoming public in early January.
Mr Bolton told ITV's Peston On Sunday: "I don't believe I have done anything wrong.
"My own personal life, it's a little bit of a mess at the moment. I need to sort that out, of course."
Asked about reports his estranged wife still did not know if their marriage was over, he replied: "My wife and I have exchanged lengthy emails on this. We have spoken a couple of times on the phone, but that is my business."
Mr Bolton is the latest in a string of people to be elected leader of Ukip.
The NEC result fuelled speculation that Nigel Farage would return to take the helm of the Eurosceptic party.
But Mr Farage's spokesman said: "There is no chance. He wouldn't consider it for a second."
The spokesman also insisted Mr Farage is "absolutely not" about to start a new political party.
Neil Hamilton, Ukip's leader in Wales, said Mr Bolton should "seek psychological help".
He said: "I support the NEC's unanimous decision to pass a vote of no confidence in Henry Bolton.
"He should now resign from Ukip immediately so we can get on with rebuilding the party without further distraction.
"If he forces us to hold an EGM, he will only humiliate himself further.
"His recent behaviour has been so irrational, he should seek psychological help."