Henry Bolton has insisted he will not quit as UKIP leader, saying it is "time to drain the swamp" of malcontents within the party.
He said UKIP's national executive committee, which passed a vote of no confidence in him, was "not fit for purpose" and must be reformed.
Speaking in Folkestone, he urged UKIP to put an end to factional infighting.
It came after 14 senior figures quit their roles, including Mr Bolton's deputy and assistant deputy.
Former UKIP leader Nigel Farage said Mr Bolton had been "pretty stupid" in the way he had handled the media over claims about his private life.
But he said he was "very pleased" that the leader was pushing for changes to the party's constitution and the national executive committee, which he said were long overdue.
"If UKIP doesn't change it will not exist in 18 months time," he said on his LBC radio show.
He said he will "wait to see" Henry Bolton's proposals to reform UKIP, before deciding whether to back him staying on as leader.
In an interview with Mr Farage, Mr Bolton hit out at those who had quit, saying: "If they had any interest in the party they would be continuing their jobs - their resignations achieve nothing in that respect."
Asked how he was coping with the media attention, Mr Bolton said: "In some ways I am enjoying navigating through all this."
UKIP's local government, education, trade and immigration spokesmen have all resigned as Mr Bolton defied growing calls to quit over offensive texts sent by his ex-girlfriend.
Ex-education spokesman David Kurten said he believed Mr Bolton had "no chance of surviving" a vote of party members, saying he did not know what the leader "hoped to achieve" by staying on.
In a statement to the media, Mr Bolton said he "respected" the party's constitutional process, which will see party members decide his future in the coming weeks.
But he said the decision to force a vote was a "distraction" from what should be the party's focus on May's local elections and achieving "true independence" for the UK after Brexit.
"I repeat I shall not be resigning as party leader."
He said he had lost confidence in the NEC, which he said was unable to take the party forward and whose shortcomings he suggested had been recognised by previous leaders.
"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.
"Likewise, it is now time to put an end to the factional in-fighting within the party and to remove those who have been a part of that. In a single phrase, it is time to 'Drain the Swamp'."
Mr Bolton, who has been under pressure over some of his former girlfriend's comments, has said another leadership contest could be financially ruinous for the party, which has staged three contests in the last 18 months.
He has also said he has ended the "romantic element" of his relationship with Jo Marney after it emerged that in the past she had sent a text saying Prince Harry's fiancee Meghan Markle would "taint" the Royal Family, leading to accusations of racism.
UKIP's leadership changes
- Nigel Farage: UKIP's long-serving leader announced his resignation on 4 July 2016, saying his "political ambition has been achieved" by the Brexit vote
- Diane James: Lasted less than three weeks after being elected in September 2016
- Nigel Farage: Returned as interim leader in October 2016
- Paul Nuttall: Elected on 28 November 2016, but quit the following June after UKIP's general election collapse
- Henry Bolton: Elected on 29 September. Is facing resignations and a vote of no confidence
But Mr Bolton has so far failed to convince many of the senior figures in the party - with the NEC's vote of no confidence in him on Sunday followed by a series of resignations on Monday.
In his resignation letter as trade spokesman William Dartmouth, a South West England MEP, told Mr Bolton his position was "untenable".
"When you became leader you said that you would make the party successful," he said. "If you still feel that way then you should resign forthwith."
Deputy leader Margot Parker, who is an East Midlands MEP, said Mr Bolton's "personal life took over the job he was elected to do".
She added: "It would be quicker and cleaner if he came to the conclusion he could go sooner rather than later.
"This is taking time away from doing the job. This puts the party in a limbo situation."
She told Mr Farage, on his LBC programme "It's a pretty wacky situation we find ourselves in" and his questioning of his colleagues' loyalty was "outrageous".
NEC member Paul Oakley told Mr Farage the party had already lost patience with Mr Bolton before the stories about his private life, adding: "His handling of the media was absolutely atrocious".
Following the vote of no confidence party members who turn up to the EGM will given a vote on whether Mr Bolton should remain in post.
UKIP, which has long campaigned to leave the EU, came top in the 2014 European elections and got the third largest vote share in the 2015 general election with 12.6% - but this plummeted to 1.8% in June - the first general election since the UK voted for Brexit.