Nigel Farage has said that he will not stand in the Newark by-election sparked by former Tory minister Patrick Mercer's decision to quit over a cash-for-questions scandal.
The Ukip leader said he did not want to do anything that would distract from the party's campaign for next month's European elections, where he predicted Ukip would cause an "earthquake in British politics".
Yesterday, Mr Farage admitted he was "tempted to stand" and said winning a seat in Westminster would "completely transform the landscape" for his party.
But today he told the BBC: "I don't want to do anything that deflects from the European election campaign, so I am not going to stand in this by-election.
"I want to focus the next three weeks on winning the European elections."
"There is a much bigger prize than the Newark by-election and that is the general election in 2015."
Speaking to the BBC on Tuesday, he had argued David Cameron would have to resign if he did win the seat, but believed he would be "finished" if he stands and loses Newark, saying: "the bubble is burst".
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Mr Mercer decided to resign after learning he faced a six-month suspension from Westminster.
The former army colonel is alleged to have tabled Commons questions and offered a Westminster security pass after signing a deal that paid him £4,000 for seeking the readmission of Fiji to the Commonwealth.
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Fiji reacts angrily to its depiction in Patrick Mercer lobbying affair
The penalty was agreed by the Commons standards committee and was due to be formally announced tomorrow.
Mr Mercer won Newark from Labour in 2005 and built up his majority to 16,000 at the last election.
Ukip came fourth with less than four per cent of the vote, but the backlash against Mr Mercer could turn the by-election into an attractive prospect for the anti-European Union party.
Mr Mercer, who has sat as an independent since quitting the Tory whip 11 months ago, last night said he accepted the committee’s verdict and apologised to his constituents for his conduct.
He admitted he was "ashamed" and had many regrets as he announced his intention to stand down as the MP for Newark after facing a six month ban from parliament.
Mr Mercer added: "As an ex-soldier I believe that when I have got something wrong you have got to fess up and get on with it.
"No point in shilly shallying and trying to avoid it. What's happened has happened and I'm ashamed of it."
A Conservative spokesman said: "We agree that Patrick Mercer needs to stand down and that there should be a by-election so the people of Newark can have a new MP."