Nigel Farage hit out at his critics this morning, after a weekend of disastrous press coverage which highlighted racism among members and chaos at the top of the party.
Amid several ongoing rows about comments made by candidates standing at the local elections this week, minister without portfolio Ken Clarke yesterday said Ukip was populated by "waifs and strays".
Speaking to ITV Daybreak, Farage said: "They have lost the argument so Ken Clarke and others have decided that, rather than going for the ball, they are going to attack the player and that is exactly what this is about."
"They know that the British public are genuinely concerned about opening up the door to Bulgaria and Romania next year.
"They are concerned because we have a million youngsters unemployed, we have wages being driven down and I am afraid a crime wave in London being caused by Romanians already."
He added: "These are tough subjects to talk about. All we are doing is talking the truth.
"There is nothing in Ukip that is racist in any way at all and Ken Clarke knows it.
"If he throws this abuse out, we will start having a proper debate."
Speaking on Sky's Murnaghan programme, Clarke said: "They of course have not been able to vet their candidates. Fringe right parties do tend to collect a number of waifs and strays...
"Some of them are saying quite different things now they are in politics then their actual views."
Asked about David Cameron's description of the party as being populated by "fruitcakes and closet racists", Mr Clarke replied: "I have met people who satisfy both those descriptions in Ukip.
"Indeed, some of the people who have assured me they are going to vote Ukip I would put in that category. I rather suspect they have never voted for me."
Boris Johnson hit out at Clarke for the comments, saying most Tories thought of Farage as a fellow Conservative.
"I think there may have been a few ill-advised insults flying around in the past couple of days," he said.
"Well, I would humbly submit that there are better ways of tackling the Ukip problem, if indeed it is really a problem at all."
The comments came amid a leaked email exchange at the top of the party in which senior figures admitted it had no policies and that its membership was too divergent for it to be able to safely construct any.
Further evidence of homophobic, racist and anti-Semitic comments from Ukip members also emerged over the last week.
The eurosceptic party says the stories are the result of a smear campaign originating in Conservative head office.
Asked about the scrutiny Ukip was now being subject to ahead of what are expected to be impressive local election results, former Liberal Democrat leader Ming Campbell said: "Welcome to test cricket."