Nigel Farage accused Jeremy Corbyn of “abject surrender” as he tore into the new Labour leader over his u-turn on the EU referendum.
This afternoon, Mr Corbyn confirmed in an email to Labour MPs that the party will be campaigning to stay in the European Union regardless of David Cameron’s renegotiation with Brussels.
The Labour leader had previously indicated he could not rule out voting to leave the organisation as the Prime Minister could trade away workers’ rights as part of a deal.
After being told the news this afternoon by The Huffington Post UK, Mr Farage reacted with shock at the speed of Mr Corbyn's change in position, having only been elected leader on Saturday.
The Ukip leader said: “The man of principle appears to have been bullied within a few days of winning the Labour leadership.
“It shows the power of the pro-EU lobby is so massive. It’s massive.”
He added: “It’s an abject surrender. It might do him a lot more harm than he realises.”
Mr Farage speculated that Mr Corbyn had adopted the firm position in order to avoid a split in the party over the issue, reminiscent of the breakaway from Labour of the Social Democrat Party in 1981.
The seeds of the SDP split were sown in the 1975 referendum on the EEC, when anti-Europeans such as Tony Benn campaigned against Labour colleagues including Europhile Roy Jenkins.
Mr Farage said: “There’s no harder thing to fight in politics than this [the EU]. It is powerful, it is big, it’s strong and Corbyn has run straight into it.
“He’s obviously decided as leader that he can’t fight every battle and he knows the potential of Europe to cause a civil war within Labour.”
He also rejected suggestions that Mr Corbyn's anti-austerity agenda would win back large numbers of former Labour voters who switched to Ukip in the last election.
He said: "I think he's a sincere man but I think he represents a strain of thinking that actually is reflective of a tiddly, tiddly segment of this population. Anyone who has voted for him thinking he’s a working class hero, no, no, they’ve got a North London, trendy, middle-class, right on guy.
"His immigration views are quite extraordinary. He thinks it’s disgraceful to have any limits at all. How’s that going to work with a massive segment of traditional Labour voters? I think he will do well with the Green vote, I think he will pick up some non-voters on the left but I think he will lose potentially to us quite a chunk of traditional Labour voters."
Mr Farage was speaking ahead of a meeting in Purfleet, Essex, as part of Ukip’s ‘Say No To The EU’ tour.
The party has organised more than 300 meetings up and down the country as part of its campaign bid to get the UK to vote to leave the EU in the referendum, which will be held before the end of 2017.
Mr Farage said his party was seizing the initiative as other anti-EU politicians were giving pro-European Union figures a head start.
Jumping on the suggestion that former Tory Cabinet Minister John Redwood was one of the country’s leading eurosceptics, Mr Farage said: “Is John Eurosceptic? If we ring John now, do you know what he’ll say? ‘Wait until the prime minister comes back!’ What use is that? Well done John, bloody brilliant.
"So what we do is we let Richard Branson, Tony Blair, Uncle Tom Cobley and all dominate the Marr show, dominate the national newspapers, spend shedloads of money and even change Corbyn’s mind, we let them run rampant in this marathon race of 26 miles and when they’ve got 13 miles, we’ll start. Well that’s good, isn’t it?
“If Mr Cameron was going for fundamental treaty change and a completely new deal for Britain, then Redwood would be fully justified in holding that position. I think we’re trying to stop some benefits for a few migrants aren’t we? And maybe get back a couple of employment laws. Anything else that you’ve heard of? It’s mindless.
“So that’s the reason I’m doing this tour. I’m doing it because of people like Redwood who are advocating entirely the wrong strategy. By the time they decide and half of those will get bought anyway, because we’ve seen it all before with Maastricht. I don’t trust any of them.
Mr Farage rejected the suggestion he had nothing new to say the electorate, despite putting forward anti-EU views as a Ukip spokesman for more than 15 years.
He said: “Frank Sinatra did pretty well singing the same song for decades, and people still kept coming along. And I daresay if you and I paid good money to go and see Tom Jones we would want Delilah! Every comedian tells the same joke for 50 years. Have the big principles changed? Not at all, not one bit.”