Nigel Farage has claimed groups backed by the trade unions are attempting to stop him speaking publicly after he failed to appear at a street party in the wake of fierce arguments between supporters and protesters.
The Ukip leader denied being frightened and "bottling" the chance to attend the event in Croydon, south London, yesterday but admitted it was "probably a good job" he had not attended in view of events at the scene.
In an interview with ITV's Good Morning Britain, the Ukip leader said he had been "helter skelter" busy making public appearances in the UK and was due to travel to Eastleigh for a public meeting last night.
"I have been assaulted twice in the campaign, I have been hit over the head with a banner, which was pretty nasty, and got an egg, which is not quite so bad," he said.
"There are people out there who are determined to stop Ukip and this is because we have had a two-party system for 100 years in this country, or two-and-a-half-party system, and are posing a threat to the establishment and people are fighting back."
Asked on the programme about his use of bodyguards and what "worried" him about ordinary members of the public, Mr Farage said: "These aren't ordinary members of the public, this is organised, these are funded organisations, predominantly backed by the trade unions, who actually want to stop me speaking. If you think about it, it isn't very democratic."
Mr Farage, who conceded in an interview with BBC2's Newsnight that Ukip had been wrong to declare that Romanian gangs were responsible for 7% of crime in the EU, told GMB that he had nothing against Romanians.
"But I have got a problem with Romania, a very big problem with Romania," he said.
"I have been there, there are three million people there in the Roma minority who are treated appallingly.
"They can't get jobs, they can't get housing, they live in the most extraordinary conditions. And they have fallen victim, many of them have fallen victim, to an organised crime gang network of a very serious dimension."
He claimed the "hysteria" over Romanians had been "stirred up" by the tabloid press and not by himself.
"When I said would people be concerned if a group of Romanian men moved in next door, these were newspaper headlines, run by our biggest tabloids, week after week, that is what stirred up the hysteria, not me," he said.
"I didn't say I would be worried, I didn't say people should be worried, I said people would be worried, because they had read all this stuff in the newspapers and they have seen the crime statistics."
Pressed on his earlier claim about the responsibility of Romanian gangs for 7% of crime in the EU, Mr Farage said: "Interestingly, if you delve down into those Europol figures, and this is stunning, 90% of all card-skimming operations across the whole of the European Union are done by Romanian and Bulgarian criminal gangs.
"The wall fell, communism went and that was a good thing, and some of those countries made the transition to being western democracies. Some of them have not yet made that transition."
Mr Farage admitted that "w e all make mistakes in life and things don't always go according to plan" and, because the party had been leading the polls ahead of tomorrow's elections, it had come under sustained pressure and "sometimes a few cracks begin to show".
But he insisted the party's popularity would continue beyond the European elections, and promised that a "higher calibre" of Ukip politicians would help the party act less like a "one-man band" in future.
"There are now people who don't just lend their votes to Ukip for European elections, they are actually Ukip voters," he told BBC Radio 4's Today programme.
"What I'm going to do over the course of the summer, and remember we are going to have a whole new load of MEPs elected, they will be a much higher calibre than anything we've ever had before.
"I am going to appoint, over the course of the summer, spokesmen to take on responsibilities for specific areas and they are the people I'm going to push forward.
"I don't think people will vote for us in a general election in numbers if they think it's a one-man band. I intend to change that over the summer."
He added: "The point is, whether we have the best MEPs or not, we are the only political party on that ballot paper tomorrow saying we want a relationship with Europe based on trade and co-operation, we want to open Britain up to trade deals with the rest of the world.
"The other three parties all want us to stay within this European Union. So there's a very clear choice for voters."
With an eye on next year's general election, Mr Farage said if his party's MPs held the balance of power, he would "do a deal with the devil" to ensure that there was a referendum on Europe - a signal that he would be prepared to support a minority Tory or Labour administration on the issue.
David Cameron has promised a public vote on membership of the EU by the end of 2017, but Mr Farage was sceptical about the pledge.
Asked if he was saying the Prime Minister was dishonourable, Mr Farage said: "I'll pass on that."
He said "one or two" Tory MPs were interested in running as joint Conservative-Ukip candidates in 2015 and he was "open to having those conversations", but predicted they would be vetoed by Mr Cameron.
"There are no lines of communication open between Tory high command and Ukip," he said. "We are considered to be the lower orders."
Mr Farage also predicted that Labour would be forced to promise a referendum, something Ed Miliband has said will only happen in the "unlikely" event of powers being transferred to Brusse ls.
He acknowledged it was "moonshine" to suggest that Ukip, which has no MPs, could win the 2015 election, but the party would target winnable seats in an effort to hold the balance of power.
In an indication of what that could mean in Westminster, he said: "I would do a deal, post the next election, I would help a minority party in Westminster, I would do a deal with the devil in those circumstances if it got us a referendum."
Shadow Cabinet Office minister Michael Dugher said: "Nigel Farage has let the cat out of the bag: a vote for Ukip is a vote for the Tories.
"Ukip's policies are more Tory than the Tories. We know David Cameron cut taxes for millionaires - but Ukip want even bigger tax cuts for millionaires. We know it's harder to see your GP under David Cameron, but Ukip think the answer is to charge people to see their GP.
"Whether it's deeper cuts to public services or scrapping workers' rights, we have confirmation that Nigel Farage is actively considering shabby political deals with the Conservatives right across the country, only days after he said he'd do a deal to keep David Cameron in Number 10.
"The message is clear: vote Ukip and you don't only get policies more extreme than the Tories, you also get David Cameron."