Nigel Farage has told Peston on Sunday he will not be backing Suzanne Evans as the next Ukip leader after her comments about rival Raheem Kassam and the party’s “toxic” image.
Ms Evans announced her leadership bid on The Andrew Marr Show on Sunday, warning that Mr Kassam would take the party too far to the right.
A fresh leadership race was sparked after Diana James resigned just 18 days into the job.
Mr Farage told ITV News Political Editor Robert Peston he had not planned to back or criticise anyone in the contest, but could not support Ms Evans after her comments.
“For her to talk about the party being toxic, for her to already declare one of the candidates who’s running, Raheem Kassam, as being far-right, I don’t view this as being a very good start.
“She may well think that herself, but that is not how Ukip members and Ukip voters feel.”
Asked if he would urge Ukip voters to back any other candidate, Mr Farage said: “Well I won’t be voting for her, not after that.”
Mr Farage said he thought Ms Evans has “ability” but “it’s just a question of political direction”.
He added: “I think to kick-off this leadership election campaign by decrying one of the declared candidates is perhaps not the start we needed.”
Ms Evans said she was confident she could win the leadership election without Mr Farage's backing.
She was unable to take part in the last leadership contest after failing to overturn a six-month suspension from the party following a number of complaints about her.
Mr Kassam said he was not "far right" and was "disappointed" with Ms Evans' attack on him.
"When she does things like this, it really undermines her, it undermines her campaign and it is an attack on a lot of the party members," he said.
Steven Woolfe was widely expected to replace Ms James as leader but has since quit the party.
He resigned just weeks after collapsing in the EU parliament following an altercation with a fellow MEP.
Mr Woolfe joined Ukip six years ago but said the party is now "riddled with infighting, proxy wars between rival camps and is run by an NEC that is not fit for purpose".
Mr Farage suggested “too much ambition” had got the better of Mr Woolfe.
He told Peston it had been a “rotten couple of weeks” for Ukip but he hoped they could “get back on track” with the new leadership campaign.
Paul Nuttall became the latest candidate to join the leadership race on Sunday, saying he would be the "unity" candidate.
Speaking about Brexit, Mr Farage said the only way for Theresa May to deliver on her promises would be to call an early general election and stand on a Brexit platform.
He said any Brexit deal had to include leaving the single market.
“I have a sense at the moment that there’s probably a Parliamentary majority in favour of us staying part of the single market,” Mr Farage said.
“If Brexit doesn’t mean Brexit by the spring of 2019, then I think Ukip in 2020 could be a really big force.”