Video report by ITV News Correspondent Angus Walker
Ukip leader Henry Bolton has refused to resign, despite facing mounting pressure for him to do so.
Ukip's ruling committee unanimously backed a vote of no confidence on Sunday and the party's deputy leader, immigration spokesman and trade and industry spokesman have all stood down from their roles, citing the fact they could not work under Mr Bolton.
Mr Bolton's leadership of the party was called into question following revelations that his girlfriend Jo Marney sent racist text messages about Meghan Markle.
Ms Marney, 25, sent a series of messages to a friend in which she made offensive comments about Prince Harry's fiancée and black people.
Among the messages, first reported in the Mail on Sunday, were remarks that Ms Markle would "taint" the Royal Family, that she had a "tiny brain" and that black people were ugly.
Following the comments, 53-year-old Mr Bolton said he had ended the "romantic element" of his relationship with Ms Marney.
Speaking on Monday, Mr Bolton said he would not be resigning, instead calling for "unity" within the Party and urging Ukip's ruling body to be reformed in a bid to "drain the swamp".
The former Army officer said he had decided not to quit since he "respected the next steps in the constitutional process", with a vote by party members on whether he should remain as leader expected in the next few weeks.
Mr Bolton added that ahead of Sunday's vote of no confidence he had asked Ukip's ruling body to "not expose the Party to the financial and political cost of pursuing that course of action [the vote], including the political cost of possibly yet another leadership contest".
ITV News Correspondent Angus Walker discusses what is next for Ukip.
Calling for "cohesion" in Ukip and rather than focusing on the leadership debate, Mr Bolton urged the Party to "concentrate on such matters as the local government election campaign and the necessity of mobilising our efforts to ensure the government delivers true independence in all areas of government and administration when we leave the European Union.
"This is the most pressing matter facing our country and I am determined not to allow the NEC to distract the Party away from participating forcefully in the Independence debate."
Mr Bolton continued that Ukip's ruling body "as presently constituted, is unfit for purpose and has severely handicapped the Party's progress and political delivery for some years, as all recent UKIP leaders will attest...
"The NEC requires significant and urgent reform.
"To that end, again during the coming weeks, I shall be proposing a new Party constitution, with a newly constituted and reformed NEC...
"In a single Phrase, it is time to 'Drain the Swamp'."
Former Ukip leader Nigel Farage has handed Mr Bolton a lifeline by backing him in an article in the Telegraph, saying the current leader could become the Party's version of Jeremy Corbyn.
"Bolton knows as well as anyone that Ukip must reform or die.
"His refusal to accept the NEC decision to quit, and his insistence on carrying out a full EGM, could provide a lifeline for Ukip.
"For this crisis is about more than Henry Bolton. It is about whether Ukip is fit for purpose.
"As one party spokesman after another resigns, I am reminded of the nightmare Jeremy Corbyn faced in 2016 when 21 members of his shadow cabinet resigned.
"Corbyn was written off by the press, but the rank and file membership saved him.
"If Bolton has the courage and the vision to introduce a new constitution, and shows that he can be a strong spokesman for Britain leaving the single market, taking back its fisheries and restoring pride in the UK, he may well surprise all of his critics too."
Yet while interviewing the Ukip leader LBC radio show, Mr Farage labelled Mr Bolton's relationship with Ms Marney as "cringe-making" but suggested "it may not be a bad thing, however - if he has the wisdom to use his profile properly".
However, after Sunday's vote of no confidence, Ukip's deputy leader, Margot Parker MEP, quit on Monday, telling Mr Bolton to relinquish the leadership in the process.
Ms Parker's announcement was quickly followed by immigration spokesman John Bickley confirmed he would not continue in his role under the current leader.
A third resignation came as trade and industry spokesman William Dartmouth MEP, confirmed he would be standing down, too.
Ukip's assistant deputy leader Mike Hookem joined the exodus saying he had lost the support of MEPs, party staff and grassroots members.
Ukip's education spokesman and London Assembly Member David Kurten also resigned, calling for Mr Bolton "to step down with dignity rather than extending the current debacle for another four weeks", as he did so.
East of England MEP Tim Aker quit as local government spokesman, saying he hoped leader Henry Bolton "does the right thing" and resigns.
While Peter Jewell resigned as Ukip's justice spokesman, and Julia Reid as environment spokeswoman, just hours after Mr Bolton defied calls to quit.