Nick Clegg and Nigel Farage will go head to head tonight in a televised showdown tonight over Britain's future in the European Union.
The Deputy Prime Minister and Ukip leader will fight to win over the public in the first of two debates between "the party of in and the party of out" being staged in the run-up to the European Parliament elections in May.
Farage's performance in the clash, which will be broadcast from 7pm on LBC and Sky News, will be intensely scrutinised in Westminster where Ukip's growing popularity is causing jitters among the main parties.
In an article on The Independent's website Farage suggested his opponent did not realise "what is about to hit him" and claimed he was initially surprised Clegg wanted the debate.
"But then his party is facing the prospect of electoral wipe-out at these elections unless they do something drastic," he wrote.
"For them, it's about survival. There is no reason why any establishment party would otherwise want to highlight the huge number of competences which Brussels now has over our lives – especially on a live broadcast and televised debate."
He added: "My position is clear, and we have the clear, pragmatic business argument on our side. A few multinationals love the EU because it drives out competition with the costs of compliance and regulation. But the backbone of this country – small and medium-sized businesses – are the ones who are looking towards Ukip's policy."
Prime Minister David Cameron showed little interest in his deputy's clash with the Ukip leader. Asked if he would be tuning in to the debate, Cameron joked: "When is it?"
He added: "I don't know what I'm doing but I'm sure it will be very interesting."
Asked if he has any tips for Clegg, he said: "No, I'm sure it'll be interesting."
Questioned on whether he would "agree with Nick" he said: "That depends what he says."
Cameron said last week the DPM wants to "sign up to everything that comes out of Brussels without asking questions".
Echoing the 2010 general election leaders' debates, the arrangements agreed for the head-to-head have been tightly controlled.
The audience has been selected to reflect the UK population as well as a spread of views on the EU debate.
Questions will be screened by an editorial panel but the parties will not see them in advance.
The party leaders will both make opening and closing statements and will have one minute to answer questions from the audience before presenter Nick Ferrari opens up the subjects to free debate.
Farage is a Ukip MEP for the South East of England and was re-elected party leader in November 2010 after a brief spell away from the helm.
Clegg, a former East Midlands MEP who speaks French, German, Spanish and Dutch, has said he wants to dispel the "myths" being peddled by "isolationists" and levelled a personal attack at the
Ukip leader, accusing him of pocketing his MEP's salary but not bothering to vote.
The second debate will be broadcast on BBC2 on April 2 and will also be broadcast by Sky News.
Cameron's official spokesman declined to say whether the Prime Minister was planning to listen to the debate.
The spokesman told a Westminster media briefing: "I don't know what his schedule holds for that particular time-slot. Other broadcast channels are available too."