Nigel Farage has called a Labour MP a "disgraceful woman" after she accused him of rubber-necking at victims of child abuse.
Interviewed at his party's North East Spring Conference in Hartlepool, he branded Rotherham's Labour MP Sarah Champion a "disgraceful woman" after she claimed his visit on Friday to her scandal-hit constituency amounted to rubber-necking.
Farage hit back, saying: "She said what happened to me in Rotherham was funny.
"So what we are going to do next week, we are going to have 30 Ukip activists outside her office and we will hold up placards and shout abusive slogans. I wonder how funny she would find that."
Farage clarified: "No, we would not do that really, but if we did do that, then South Yorkshire Police would move us in short order, which didn't happen yesterday."
The Ukip leader said it was "very good" for his party's chances that the electorate was getting bored with negative campaigning by Labour and the Tories.
"They are getting to see actually that the Labour and Conservative parties have very little to say other than, 'aren't they ghastly?'," he said.
"This negative campaigning, I don't think it works. We have quite deliberately got some positive messages coming up in this election campaign."
A breast-feeding woman was photographed among the Rotherham protesters, in response to controversial remarks he made about nursing mothers.
Farage said: "The thought of militant breast-feeders, I have never come across this before - all based on a complete misquote that I didn't make in the first place."
Speaking about anti-Ukip demonstrators barracking him during the campaign, he said: "We have a history of protest in British politics, there's nothing wrong with that, I have protested before outside meetings.
"What they should not be able to do is stop an elected politician going about his or her business or to threaten them with violence. Unfortunately, I have been encountering more of that over the course of the past 18 months or so."
But the Ukip campaign was going well, he said, adding: "We have two big parties who are telling the British electorate, with their friends in the newspaper industry, that there is a binary choice in this election and nobody else matters.
"That message does not resonate (with electors).
"We are only a month in and half the country is bored to death already so from my perspective the opportunity to walk through the middle of this and come in with a positive message I think is very good."