Polls show Mr Johnson is likely to win a comprehensive victory when the result of the Tory leadership race is announced tomorrow.
But in a sign of difficulties he faces once in Downing Street, senior ministers opposing No Deal including Philip Hammond and David Gauke announced they would quit the Government if he becomes Prime Minister.
Boris Johnson will have a wafer-thin Commons majority of just four when he becomes PM, which could fall to two if the Tories lose a by-election next month. His Brexit plan faced a double blow last night before he even enters No 10
They are among half a dozen ministers expected to resign on Wednesday, when Theresa May leaves office, rather than being sacked.
In addition, six more MPs were rumoured to be planning to defect to the Liberal Democrats if he becomes the party’s new leader.
And Mr Johnson is not just facing trouble from within his own party. Yesterday the Irish government took a hardline stance against his demand for a better Brexit deal.
Ireland’s deputy prime minister Simon Coveney insisted the EU would not renegotiate the withdrawal agreement and rejected outright the idea of a time limit on the Northern Ireland backstop.
But in a sign of difficulties he faces once in Downing Street, senior ministers opposing No Deal including Philip Hammond and David Gauke (above) announced they would quit the Government if he becomes Prime Minister
Last night Mr Johnson was finalising the list of senior Downing Street staff to join him in No 10 and work in his Cabinet.
Expectations of his victory were raised by a ConservativeHome poll showing up to 73 per cent of Tory members back him for leader, in what would be a landslide over Jeremy Hunt.
The result will be announced shortly after 11am tomorrow. Mrs May will conduct her final Prime Minister’s Questions on Wednesday before she goes to Buckingham Palace to resign.
Mr Johnson is then expected to make his first speech as PM outside No 10 at around 5pm and begin making Cabinet appointments later in the evening.
Chancellor Phillip Hammond is also among half a dozen ministers expected to resign on Wednesday, when Theresa May leaves office, rather than being sacked
Margot James, who resigned as a culture minister last week to support efforts to stop Parliament being suspended, is thought to be among the group who have discussed defecting to the Liberal Democrats
He has promised to leave the EU ‘do or die’ on October 31, and last week toughened his Brexit stance by insisting he would not accept minor changes to the Irish backstop.
But up to half a dozen ministers in the so-called ‘Gaukeward Squad’ – named after Justice Secretary Mr Gauke – strongly opposed to No Deal are expected to walk out on the day and begin organising against him from the backbenches.
Mr Johnson will have a wafer-thin Commons majority of just four when he becomes PM, which could fall to two if the Tories lose a by-election next month.
Will Tory MPs join Lib Dems?
Six Tory MPs may defect to the Liberal Democrats if Boris Johnson is anointed Conservative leader tomorrow, it was claimed yesterday.
The rebel group are due to hold talks with the pro-Remain party this week and could discuss voting against Mr Johnson in a vote of no confidence, The Sunday Times reported.
It is said they could even consider joining the Lib Dems – depriving Mr Johnson of a majority even with the backing of the DUP.
Sir Ed Davey, who served as Lib Dem energy minister in the coalition cabinet with leading Tory remainers, is understood to have been approached by Conservatives desperate to stop Mr Johnson.
It would only take two desertions to wipe out the Tory majority and the Conservatives are also widely expected to lose a seat in an upcoming by-election in Brecon and Radnorshire.
Margot James, who resigned as a culture minister last week to support efforts to stop Parliament being suspended, is thought to be among the group who have discussed defecting.
Yesterday she said she was not considering leaving ‘at the moment’, adding: ‘I want to stay working with this group in the Conservative Party as I do think there’s a chance of getting somewhere.’
Yesterday morning Mr Hammond announced he would quit before he is pushed and repeated his determination to stop a ‘catastrophic’ No Deal Brexit.
Asked on the BBC’s Andrew Marr Show if he thought he would be sacked, he replied: ‘No, I’m sure I’m not going to be sacked because I’m going to resign before we get to that point.
‘Assuming that Boris Johnson becomes the next prime minister, I understand that his conditions for serving in his Government would include accepting a No Deal exit on October 31, and it’s not something I could ever sign up to.
‘It’s very important that the Prime Minister is able to have a Chancellor who is closely aligned with him in terms of policy, and I therefore intend to resign to Theresa May before she goes to the Palace to tender her own resignation on Wednesday.’
The result will be announced shortly after 11am tomorrow. Mrs May will conduct her final Prime Minister’s Questions on Wednesday before she goes to Buckingham Palace to resign
Mr Gauke told The Sunday Times he would also quit, adding: ‘If the test of loyalty to stay in the Cabinet is a commitment to support No Deal on October 31 – which, to be fair to him, Boris has consistently said – then that’s not something I’m prepared to sign up to.
‘I recognise that this spell in government is coming to an end. Given that I’ve been in the Cabinet since Theresa May came to power, I think the appropriate thing is for me to resign to her.’
Mr Hammond said Parliament ‘does have a way of preventing a No Deal exit on October 31 without parliamentary consent’, adding: ‘I intend to work with others to ensure Parliament uses its power to make sure that the new Government can’t do that.’
Several other ministers could also quit on the day, sources suggested, including International Development Secretary Rory Stewart, Foreign Office minister Alan Duncan, health minister Stephen Hammond and energy minister Claire Perry.
However, Business Secretary Greg Clark has told friends he will not quit and could remain in the Government.
Irish deputy Mr Coveney rebuffed suggestions the EU would compromise with Mr Johnson on the existing Brexit deal ‘just because there’s a change in personality as British Prime Minister’, saying: ‘We’re simply not going to move away from that Withdrawal Agreement.
‘The facts don’t change around Brexit. The complexity doesn’t change. The vulnerabilities on the island of Ireland don’t change.
‘The EU I think has made it very clear that we want to engage with the new British Prime Minister, we want to avoid a No Deal Brexit.’
He described Mr Johnson’s approach was ‘give me what I want or I’m going to burn the house down for everybody’.