Boris Johnson’s Brexit stance risks driving millions of Conservative voters into the hands of Remain-backing parties like the Liberal Democrats and Scottish National Party in the upcoming election, a senior Tory has warned.

Former defence secretary Sir Michael Fallon is the most prominent supporter of the prime minister to go public with a warning to Mr Johnson not to further alienate Remain voters and to stick to the Tories’ promise to take Britain out of the EU in an “orderly” way.

The PM’s vow to leave with or without a deal on 31 October and his assertion that he would rather be “dead in a ditch” than delay Brexit have alarmed some Tories.

Thousands protest after Boris Johnson requests to suspend parliament Show all 29 1 /29 Thousands protest after Boris Johnson requests to suspend parliament Thousands protest after Boris Johnson requests to suspend parliament Houses of Parliament An anti-Brexit supporter raises a sign during a protest in front of the Houses of Parliament in central London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson maneuvered on Wednesday to give his political opponents even less time to block a no-deal Brexit before the Oct. 31 withdrawal deadline, winning Queen Elizabeth II's approval to suspend Parliament. (AP Photo/Vudi Xhymshiti) Vudi Xhymshiti AP Thousands protest after Boris Johnson requests to suspend parliament Downing Street Anti-Brexit demonstrators hold placards as they protest outside of Downing Street in London on August 28, 2019. - British Prime Minister Boris Johnson sparked fury Wednesday among pro-Europeans and MPs opposed to a no-deal Brexit by forcing the suspension of parliament weeks before Britain's EU departure date. The pound slid on the surprise news, which opponents branded a "coup" and a "declaration of war" but Johnson claimed was necessary to allow him to pursue a "bold and ambitious" new domestic legislative agenda. (Photo by DANIEL SORABJI / AFP)DANIEL SORABJI/AFP/Getty Images DANIEL SORABJI AFP/Getty Images Thousands protest after Boris Johnson requests to suspend parliament Houses of Parliament Anti-Brexit supporters take part in a protest in front of the Houses of Parliament in central London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson maneuvered on Wednesday to give his political opponents even less time to block a no-deal Brexit before the Oct. 31 withdrawal deadline, winning Queen Elizabeth II's approval to suspend Parliament. (AP Photo/Vudi Xhymshiti) Vudi Xhymshiti AP Thousands protest after Boris Johnson requests to suspend parliament Houses of Parliament to Downing Street TOPSHOT - Anti-Brexit demonstrators hold placards as they take part in a protest march from Britain's Houses of Parliament to Downing Street in London on August 28, 2019. - British Prime Minister Boris Johnson announced Wednesday that the suspension of parliament would be extended until October 14 -- just two weeks before the UK is set to leave the EU -- enraging anti-Brexit MPs. MPs will return to London later than in recent years, giving pro-EU lawmakers less time than expected to thwart Johnson's Brexit plans before Britain is due to leave the European Union on October 31. (Photo by DANIEL SORABJI / AFP)DANIEL SORABJI/AFP/Getty Images DANIEL SORABJI AFP/Getty Images Thousands protest after Boris Johnson requests to suspend parliament Downing Street Anti-Brexit supporters gather outside the Prime Minister's residence 10 Downing Street in London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson asked Queen Elizabeth II on Wednesday to suspend Parliament, throwing down the gauntlet to his critics and causing outrage among opposition leaders who will have even less time to thwart a no-deal Brexit. (AP Photo/Matt Dunham) Matt Dunham AP Thousands protest after Boris Johnson requests to suspend parliament Houses of Parliament LONDON, ENGLAND - AUGUST 28: Pro-EU supporters protest outside the Houses of Parliament on August 28, 2019 in London, England. British Prime Minister Boris Johnson has written to Cabinet colleagues telling them that his government has requested the Queen suspend parliament for longer than the usual conference season. Parliament will return for a new session with a Queen's Speech on 14 October 2019. Some Remain supporting MPs believe this move to be a ploy to hinder legislation preventing a No Deal Brexit. (Photo by Peter Summers/Getty Images) Peter Summers Getty Images Thousands protest after Boris Johnson requests to suspend parliament Houses of Parliament epa07799808 A protestor outside the Houses of Parliament in Westminster, London, Britain, 28 August 2019. The UK government is to suspend Parliament after the summer break, a move that might block MPs from voting against a possible no-deal Brexit.. EPA/WILL OLIVER WILL OLIVER EPA Thousands protest after Boris Johnson requests to suspend parliament Houses of Parliament Anti-Brexit supporters take part in a protest near the Houses of Parliament in central London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson asked Queen Elizabeth II on Wednesday to suspend Parliament, throwing down the gauntlet to his critics and causing outrage among opposition leaders who will have even less time to thwart a no-deal Brexit. (AP Photo/Matt Dunham) Matt Dunham AP Thousands protest after Boris Johnson requests to suspend parliament Whitehall TOPSHOT - Demonstrators hold placards as they protest on Whitehall, near the entrance to Downing Street in London on August 28, 2019. - British Prime Minister Boris Johnson sparked fury Wednesday among pro-Europeans and MPs opposed to a no-deal Brexit by forcing the suspension of parliament weeks before Britain's EU departure date. The pound slid on the surprise news, which opponents branded a "coup" and a "declaration of war" but Johnson claimed was necessary to allow him to pursue a "bold and ambitious" new domestic legislative agenda. (Photo by DANIEL SORABJI / AFP)DANIEL SORABJI/AFP/Getty Images DANIEL SORABJI AFP/Getty Images Thousands protest after Boris Johnson requests to suspend parliament Houses of Parliament Anti-Brexit supporters take part in a protest at College Green near the Houses of Parliament in central London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson maneuvered Wednesday to give his political opponents even less time to block a no-deal Brexit before the Oct. 31 withdrawal deadline, winning Queen Elizabeth II's approval to suspend Parliament. (AP Photo/Matt Dunham) Matt Dunham AP Thousands protest after Boris Johnson requests to suspend parliament Anti-Brexit supporters take part in a protest at College Green near the Houses of Parliament in central London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson maneuvered Wednesday to give his political opponents even less time to block a no-deal Brexit before the Oct. 31 withdrawal deadline, winning Queen Elizabeth II's approval to suspend Parliament. (AP Photo/Matt Dunham) Matt Dunham AP Thousands protest after Boris Johnson requests to suspend parliament Protestors from the European Movement in Scotland hold a walking vigil on the Royal Mile, Edinburgh, to demonstrate against Prime Minister Boris Johnson temporarily closing down the Commons from the second week of September until October 14 when there will be a Queen's Speech to open a new session of Parliament. PRESS ASSOCIATION Photo. Picture date: Wednesday August 28, 2019. See PA story POLITICS Brexit. Photo credit should read: Jane Barlow/PA Wire Jane Barlow PA Thousands protest after Boris Johnson requests to suspend parliament Anti-Brexit supporters shout slogans as they gather outside the Prime Minister's residence 10 Downing Street in London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson asked Queen Elizabeth II on Wednesday to suspend Parliament, throwing down the gauntlet to his critics and causing outrage among opposition leaders who will have even less time to thwart a no-deal Brexit. (AP Photo/Matt Dunham) Matt Dunham AP Thousands protest after Boris Johnson requests to suspend parliament Anti-Brexit supporters take part in a protest at College Green near the Houses of Parliament in central London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson maneuvered Wednesday to give his political opponents even less time to block a no-deal Brexit before the Oct. 31 withdrawal deadline, winning Queen Elizabeth II's approval to suspend Parliament. (AP Photo/Matt Dunham) Matt Dunham AP Thousands protest after Boris Johnson requests to suspend parliament Anti-Brexit supporters take part in a protest at College Green near the Houses of Parliament in central London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson maneuvered Wednesday to give his political opponents even less time to block a no-deal Brexit before the Oct. 31 withdrawal deadline, winning Queen Elizabeth II's approval to suspend Parliament. (AP Photo/Matt Dunham) Matt Dunham AP Thousands protest after Boris Johnson requests to suspend parliament Anti-Brexit supporters gather outside the Prime Minister's residence 10 Downing Street in London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson asked Queen Elizabeth II on Wednesday to suspend Parliament, throwing down the gauntlet to his critics and causing outrage among opposition leaders who will have even less time to thwart a no-deal Brexit. (AP Photo/Matt Dunham) Matt Dunham AP Thousands protest after Boris Johnson requests to suspend parliament Anti-Brexit supporters take part in a protest at College Green near the Houses of Parliament in central London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson maneuvered Wednesday to give his political opponents even less time to block a no-deal Brexit before the Oct. 31 withdrawal deadline, winning Queen Elizabeth II's approval to suspend Parliament. (AP Photo/Matt Dunham) Matt Dunham AP Thousands protest after Boris Johnson requests to suspend parliament Shadow home secretary Diane Abbott addresses protesters outside the Houses of Parliament, London, to demonstrate against Prime Minister Boris Johnson temporarily closing down the Commons from the second week of September until October 14 when there will be a Queen's Speech to open a new session of Parliament. PRESS ASSOCIATION Photo. Picture date: Wednesday August 28, 2019. See PA story POLITICS Brexit. Photo credit should read: Kirsty O'Connor/PA Wire Kirsty O'Connor PA Thousands protest after Boris Johnson requests to suspend parliament epa07799846 Protesters gather outside the Houses of Parliament in Westminster, London, Britain, 28 August 2019. The UK government is to suspend Parliament after the summer break, a move that might block MPs from voting against a possible no-deal Brexit. EPA/WILL OLIVER WILL OLIVER EPA Thousands protest after Boris Johnson requests to suspend parliament Anti-Brexit supporters gather outside the Prime Minister's residence 10 Downing Street in London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson asked Queen Elizabeth II on Wednesday to suspend Parliament, throwing down the gauntlet to his critics and causing outrage among opposition leaders who will have even less time to thwart a no-deal Brexit. (AP Photo/Matt Dunham) Matt Dunham AP Thousands protest after Boris Johnson requests to suspend parliament Anti-Brexit supporters carry a flare near the Cenotaph in central London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson asked Queen Elizabeth II on Wednesday to suspend Parliament, throwing down the gauntlet to his critics and causing outrage among opposition leaders who will have even less time to thwart a no-deal Brexit. (AP Photo/Matt Dunham) Matt Dunham AP Thousands protest after Boris Johnson requests to suspend parliament Anti-Brexit demonstrators hold placards as they protest outside of Downing Street in London on August 28, 2019. - British Prime Minister Boris Johnson sparked fury Wednesday among pro-Europeans and MPs opposed to a no-deal Brexit by forcing the suspension of parliament weeks before Britain's EU departure date. The pound slid on the surprise news, which opponents branded a "coup" and a "declaration of war" but Johnson claimed was necessary to allow him to pursue a "bold and ambitious" new domestic legislative agenda. (Photo by DANIEL SORABJI / AFP)DANIEL SORABJI/AFP/Getty Images DANIEL SORABJI AFP/Getty Images Thousands protest after Boris Johnson requests to suspend parliament Anti-Brexit demonstrators hold placards as they protest outside of Downing Street in London on August 28, 2019. - British Prime Minister Boris Johnson sparked fury Wednesday among pro-Europeans and MPs opposed to a no-deal Brexit by forcing the suspension of parliament weeks before Britain's EU departure date. The pound slid on the surprise news, which opponents branded a "coup" and a "declaration of war" but Johnson claimed was necessary to allow him to pursue a "bold and ambitious" new domestic legislative agenda. (Photo by DANIEL SORABJI / AFP)DANIEL SORABJI/AFP/Getty Images DANIEL SORABJI AFP/Getty Images Thousands protest after Boris Johnson requests to suspend parliament LONDON, ENGLAND - AUGUST 28: Pro-EU supporters protest outside the Houses of Parliament on August 28, 2019 in London, England. British Prime Minister Boris Johnson has written to Cabinet colleagues telling them that his government has requested the Queen suspend parliament for longer than the usual conference season. Parliament will return for a new session with a Queen's Speech on 14 October 2019. Some Remain supporting MPs believe this move to be a ploy to hinder legislation preventing a No Deal Brexit. (Photo by Peter Summers/Getty Images)(Photo by Peter Summers/Getty Images) Peter Summers Getty Images Thousands protest after Boris Johnson requests to suspend parliament Anti-Brexit supporters continue to participate in a late evening protest in front of the Houses of Parliament in central London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson maneuvered on Wednesday to give his political opponents even less time to block a no-deal Brexit before the Oct. 31 withdrawal deadline, winning Queen Elizabeth II's approval to suspend Parliament. (AP Photo/Vudi Xhymshiti) Vudi Xhymshiti AP Thousands protest after Boris Johnson requests to suspend parliament London metropolitan police talk with anti-Brexit supporters in front of the Houses of Parliament in central London, Wednesday, Aug. 28, 2019. British Prime Minister Boris Johnson maneuvered on Wednesday to give his political opponents even less time to block a no-deal Brexit before the Oct. 31 withdrawal deadline, winning Queen Elizabeth II's approval to suspend Parliament. (AP Photo/Vudi Xhymshiti) Vudi Xhymshiti AP Thousands protest after Boris Johnson requests to suspend parliament LONDON, ENGLAND - AUGUST 28: A Pro-EU supporter raises her fist during a protest outside the Houses of Parliament on August 28, 2019 in London, England. British Prime Minister Boris Johnson has written to Cabinet colleagues telling them that his government has requested the Queen suspend parliament for longer than the usual conference season. Parliament will return for a new session with a Queen's Speech on 14 October 2019. Some Remain supporting MPs believe this move to be a ploy to hinder legislation preventing a No Deal Brexit. (Photo by Peter Summers/Getty Images) Peter Summers Getty Images Thousands protest after Boris Johnson requests to suspend parliament LONDON, ENGLAND - AUGUST 28: Pro-EU supporters protest outside the Houses of Parliament on August 28, 2019 in London, England. British Prime Minister Boris Johnson has written to Cabinet colleagues telling them that his government has requested the Queen suspend parliament for longer than the usual conference season. Parliament will return for a new session with a Queen's Speech on 14 October 2019. Some Remain supporting MPs believe this move to be a ploy to hinder legislation preventing a No Deal Brexit. (Photo by Peter Summers/Getty Images)(Photo by Peter Summers/Getty Images) Peter Summers Getty Images Thousands protest after Boris Johnson requests to suspend parliament LONDON, ENGLAND - AUGUST 28: Pro-EU supporters protest outside the Houses of Parliament on August 28, 2019 in London, England. British Prime Minister Boris Johnson has written to Cabinet colleagues telling them that his government has requested the Queen suspend parliament for longer than the usual conference season. Parliament will return for a new session with a Queen's Speech on 14 October 2019. Some Remain supporting MPs believe this move to be a ploy to hinder legislation preventing a No Deal Brexit. (Photo by Peter Summers/Getty Images)(Photo by Peter Summers/Getty Images) Peter Summers Getty Images

And there is unease in the party at his decision to expel 21 MPs, including two former chancellors and the grandson of Sir Winston Churchill, for backing anti-no deal legislation in the Commons.

Sir Michael, who has announced he will stand down as an MP at the coming election, said he hoped the 21 would be allowed to appeal against the decision to strip them of the Tory whip and bar them from being Conservative candidates.

He told BBC Radio 4’s Today programme: ”I would hope there would be some kind of appeal mechanism that they can find now so they get the chance to state their case.

“I also worry that it sends the wrong message to Remainers, particularly in my party.”

Sir Michael said: “I think, by definition, some 5 million Conservatives must have voted Remain and I think we have got to be very careful not to drive them into the hands of Remainer parties like the Liberal Democrats in England or the Scottish nationalists in Scotland."

He added: “At the end of October we are doing a huge thing, one of the biggest things we’ve done in this country since the Second World War, and it’s very important that we do try and take those who voted Remain - nearly half the country - with us.”

(REUTERS (REUTERS)

The Sevenoaks MP, who has served in the Commons for more than 30 years, said he hoped it was not too late to reach a withdrawal agreement with Brussels.

With Mr Johnson due to meet Irish Taoiseach Leo Varadkar in Dublin on Monday and a crunch EU summit coming on 17 October, Sir Michael said the government “clearly hopes that at the last moment our partners would see that no-deal is damaging for everybody”.

And he added: “We pledged to withdraw in an orderly way. There are seven weeks left to try to find an agreement… There is still time to find a way through this with some kind of compromise agreement. It’s very important that those who voted Remain do feel that they are wanted with us on this voyage to a new future.”

Sir Michael said he had voted for Mr Johnson in the Tory leadership contest as “somebody who would bring fresh energy and ambition to this Brexit process” and backed his strategy of setting a final date of 31 October.