He said that if there were a proper national debate about Europe in the run up to polling day UKIP, which is fielding 69 candidates for the 72 seats up for grabs, would experience another "surge" in public support.
"I think our potential in this election isn't just that we could beat the Liberal Democrats again. I think our potential in this particular election is that we could beat Gordon Brown's Labour Party.
"I am sure that the humiliation of being beaten into fourth place by UKIP would bring down the prime minister and given that he turned his back on us, having made a solemn pledge to give us a referendum, that is something I personally would not lose any sleep over."
He also addressed concerns about former UKIP MEPs Tom Wise, who was suspended after being investigated by EU anti-fraud watchdogs, and Ashley Mote, who was jailed for housing benefit fraud.
Mr Farage told reporters: "We have had our fair share of bad apples but I would point out that where we have had elected MEPs that have behaved badly and broken trust with us we have dealt with it absolutely ruthlessly by getting rid of them immediately."
He said this contrasted with the major parties who he said "do everything they can to protect those who have not behaved well."
He said UKIP, which sits with other Eurosceptic parties as part of the Independence and Democracy group, had provided a voice of opposition to the EU within the European Parliament for the first time.
Because of that, the party had "held true" to the 2.7 million people who voted for it in 2004, he said, and it had played a "key role" in the successful campaign against the Lisbon Treaty in Ireland.
Mr Farage claims to have transformed the party, with much younger candidates, including five black or Asian people. Marta Andreasen, who was sacked as the EU's chief accountant after exposing suspect practices, is standing for the party in the South East of England and London.
He also made a direct appeal to disaffected voters considering supporting the British National Party, which Labour fears is poised to make a breakthrough in the North of England.
"There have been people in local council by-elections who have been going out and voting BNP, holding their nose because they want to send a message that they are not happy with what is happening.
"And we are going to say very loudly and very clearly to those people - we are a patriotic party, we believe in proper immigration controls in this country but we do so from a non-racist and non-sectarian perspective.
"In fact the only people who will stop the BNP from making an electoral breakthrough in the North of England are the UK Independence Party and we intend to do that."
He also criticised Labour deputy leader Harriet Harman's suggestion in an interview with the Financial Times that mainstream parties should not share a platform with the BNP and should avoid campaigning on issues that stoke sentiment against foreigners.
He said: "This is a ludicrous suggestion. This is a European election for goodness sake and it is Europe which determines most of our immigration and asylum policy. If we can't talk about these policies when we're about to elect those who represent us in Europe when on earth can we?"
Mr Farage pointed to a council by-election result on Thursday in Hartlepool, which is a stronghold for UKIP, where it came second to Labour.
He added: "Our message is not negative. Our message is we want friendship and free trade. We want to be good neighbours but we do not want is to be part of this political union."
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