General election: Tories facing challenge from Brexit Party across the country after Boris Johnson rejects Nigel Farage’s pact offer

Prime minister warned that Brexit Party standing ‘in every single seat’ will do more damage to Tories than Labour

Boris Johnson’s hopes of victory at next month’s general election have been dealt a serious blow after Nigel Farage vowed to field Brexit Party candidates in every seat unless the prime minister ditches his EU withdrawal deal.

Senior Tories had hoped that Mr Farage would agree to stand aside in most constituencies to give the Tories a free run, but the Brexit Party leader insisted he would do so only in the unlikely scenario that Mr Johnson scrapped his “dreadful” deal.

And Mr Johnson swiftly rejected the Brexit Party leader’s offer of an alliance, telling Sky News: “I’ve ruled out a pact with everybody because I don’t think it’s sensible to do that. We’re proud of our beliefs, we’re proud of our one-nation Conservatism.”

Announcing his strategy for the 12 December poll amid significant speculation over his intentions, Mr Farage said he was planning to field candidates in “every single seat in England, Scotland and Wales”, unless Mr Johnson promised to take the UK out of the EU with only a slimmed-down free trade agreement.

With the prime minister dismissing proposals for a pact and the prospect of him dropping his deal virtually nil, Mr Farage is now all but certain to push ahead with a full national campaign in the coming weeks.

Experts said this was “not good news” for Mr Johnson and was likely to harm the Tories significantly more than Labour.

Some Conservatives have long feared that the Brexit Party could split the pro-Brexit vote in key Leave-backing constituencies where the Tories will need to do well if they are to have any hope of securing a majority.

While Mr Farage claimed that his party posed as much of a threat to Labour as it did to the Conservatives, polling experts said this was not the case.

Professor John Curtice of Strathclyde University told The Independent: “It’s not good news for the Conservatives because it’s more likely that the Brexit Party will damage them than the Labour Party.”

He continued: “For every one voter who has moved from Labour to the Brexit Party, there are two that have moved from the Conservatives to the Brexit Party.

“The crucial question is what would people have done if the Brexit Party weren’t standing? It’s one of those counterfactual worlds where we don’t know the answer because it never existed, but it is highly unlikely that more people would have voted for the Labour Party than for the Conservatives.”

Professor Curtice said Mr Farage’s offer to Mr Johnson was evidence of the Brexit Party’s ability to damage the Conservatives’ electoral prospects, saying: “If Farage believes he’s going to damage Labour, why does he think that by saying to Boris Johnson ‘I’ll call off the troops”, that is going to appeal to Johnson? The argument doesn’t stand up.”

Mr Johnson insisted that Leave-backing voters can only be sure of getting Brexit if they elect a Conservative government, saying “the only way to get this thing done is to vote for us”.

He told ITV News: “If you vote for any other party, the risk is you’ll just get Jeremy Corbyn, the Labour Party, dither and delay, not just one referendum next year but two referendums.”

The prime minister also defended his “fantastic deal”, saying it “delivers everything that people wanted from the Brexit referendum”.

Mr Farage used his party’s campaign launch in Westminster earlier in the day to make a “”very big, generous offer” to Mr Johnson that he claimed would hand the Tories a “big stonking majority”.

He was speaking the day after Donald Trump claimed in an interview with Mr Farage for LBC that the Tories and Brexit Party working together would be an “unstoppable force”.

Mr Farage said the terms of his offer were that Mr Johnson adopt the “totally reasonable position” of giving up hopes of securing a comprehensive Brexit deal and instead seeking only a streamlined trade deal. This should be completed by 1 July next year or the UK should leave without any deal at all, he added.

He said: “If it was done, Boris Johnson would win a very big majority and on that manifesto we really could get Brexit done. In fact, to quote a friend of mind, we’d become an unstoppable force.”