Nigel Farage has said his decision to drop plans to stand Brexit Party candidates in more than 300 constituencies will put Britain “on the best possible course for future success”.
The Brexit Party leader said he had taken the “difficult decision” not to contest the 317 seats held by the Tories at the last election amid fears it could lead to a hung parliament and a second referendum.
The announcement was welcomed by the Prime Minister who said it was recognition that only the Conservatives could “get Brexit done”.
However, opposition parties said it showed the Tories and the Brexit Party were now “one and the same”.
Writing for The Daily Telegraph, Mr Farage said: “Few decisions in politics are easy and the one I have just made is no exception.
“But after weighing up the situation as carefully as I have considered anything in my life, I believe The Brexit Party’s general election strategy of not contesting the 317 seats won by the Conservatives in 2017 will put Britain on the best possible course for future success.
“It should also kill off the idea of a second referendum.”
He added: “Now, The Brexit Party will focus its energies on fighting every seat held by Labour, which has betrayed more than five million of its voters, and all the Remainer parties.
“If we can win some of these seats, our presence in parliament will keep Boris Johnson honest and help to deliver Brexit.
“I have no great love for the Tories, but I can see that by giving Johnson half a chance we will prevent a second referendum. To me, that is the single most important thing for Britain. No matter how it is achieved.”
Mr Farage had previously threatened to stand candidates in some 600 seats unless Mr Johnson abandoned his withdrawal deal with the EU.
But after the Conservatives rejected his offer of a “Leave alliance” he came under intense pressure from within his own party not to risk splitting the pro-Brexit vote.
Meanwhile, the Financial Times reported that Mr Farage has refused to deny that he could further help Mr Johnson by standing down Brexit candidates in Labour seats.
“I’ve not considered this at this moment in time,” he said, according to the FT, adding: “But there isn’t much time.”
Asked if he might “back-pedal” and tacitly back Tory candidates in marginal seats, Mr Farage told the Telegraph: “I have just taken 48 hours to make this decision – allow this one to settle first.”
Mr Farage claimed he was offered a peerage last Friday, according to the Daily Mirror.
“Ridiculous – the thought they can buy me, a high-paid job; but I’m not interested, I don’t want to know,” he told the newspaper.
Addressing a Brexit Party rally in Hartlepool, Mr Farage said he had decided to pull back amid concerns his party could have let in significant numbers of Liberal Democrats – opening up the prospect of a second referendum.
“I think this announcement today prevents a second referendum from happening,” he said.
“And that to me, I think right now, is the single most important thing in our country.
“So in a sense we now have a Leave alliance, it’s just that we’ve done it unilaterally.
“We’ve decided ourselves that we absolutely have to put country before party and take the fight to Labour.”
Mr Farage said he still believed the Withdrawal Agreement negotiated with Brussels would not deliver “the Brexit we voted for” in the 2016 referendum.
However, he said he had been encouraged by statements from Mr Johnson at the weekend saying he would not extend the planned transition period beyond the end of 2020 and that he would seek a “super-Canada-plus” style free trade agreement with the EU.
Labour leader Jeremy Corbyn said Mr Farage’s move could pave the way to a US trade deal, giving American pharmaceutical companies access to the NHS.
“One week ago Donald Trump told Nigel Farage to make a pact with Boris Johnson. Today, Trump got his wish. This Trump alliance is Thatcherism on steroids,” he said.
Mr Farage wrote in the Telegraph: “I have tried over recent months to build a Leave alliance between The Brexit Party, the Tories and some Labour figures.
“I have done my best to push the idea that putting country before party at this point is the right thing to do. But this has come to nought.”