Boris Johnson's message to Theresa May at JCB Brexit speech
JCB bosses at the Rocester plant say they have no concern about Brexit
Andrew Woodcock, Press Association Political Editor
Boris Johnson speaking at JCB Staffordshire
Boris Johnson has called on Theresa May to stop "dithering" and tell the EU that Britain will not accept the controversial backstop arrangement designed to avoid a hard border in Ireland.
The former foreign secretary dismissed calls for the Prime Minister to rule out a no-deal Brexit, insisting it was "overwhelmingly likely" Brussels will offer an improved agreement following the crushing defeat of Mrs May's plan in Parliament.
Speaking as Mrs May continued intensive discussions to draw up a Plan B to be unveiled on Monday, Mr Johnson insisted that the UK must go ahead with EU withdrawal on March 29, insisting it would be "shameful" to seek to delay Brexit by asking for an extension of the Article 50 negotiation process.
Boris Johnson in Staffordshire
The Prime Minister was meeting "a large number" of Cabinet ministers - individually and in groups - at 10 Downing Street to discuss talks she has held over the past two days with opposition party leaders and MPs from all sides of the Brexit debate.
Mrs May spoke with all party leaders except Jeremy Corbyn, who snubbed the talks because the PM refused to rule out no deal.
She also spoke by phone on Thursday evening with German Chancellor Angela Merkel and Dutch Prime Minister Mark Rutte.
Live: Boris Johnson gives Brexit speech at JCB Staffordshire plant
A spokesman for the European Commission said that president Jean-Claude Juncker expected to speak to Mrs May, at her request, on Friday afternoon.
Following reports that civil servants had been asked to draw up contingency plans for an early general election, a Downing Street spokeswoman said that Mrs May was ruling out a snap poll.
Answering questions following his high-profile speech at JCB headquarters in Staffordshire, Mr Johnson declined to say whether he would back Mrs May to lead the Tories into an election if one was called.
"I think most people in this country feel they have had quite enough elections," he said.
"I certainly do.
"I think it highly unlikely that that would be the outcome. A snap election is not the right way through."
The former figurehead of the Vote Leave campaign sought to distance himself from the group's controversial adverts about immigration from Turkey during the 2016 campaign.
Vote Leave produced adverts posted widely on social media which stated that "Turkey (population 76 million) is joining the EU" and "Britain's new border is with Syria and Iraq".
Some included images of people in Turkey with large red arrows pointing towards the UK.
Boris Johnson has a message for the Prime Minister
But Mr Johnson insisted: "I didn't say anything about Turkey in the referendum ... Since I made no remarks, I can't disown them."
He said he had always made clear that immigration "can be a wonderful thing", so long as it is "controlled".
Mr Johnson rejected warnings about the possible impact of a no-deal Brexit, insisting: "Whatever the doomsters may say about Britain after March 29 ... there will be no shortage of Mars bars, we will still have potable drinking water in Britain. The planes will fly, the ferries will ply."
He called on the Government to "fire up the engines, stop dithering, emulate the spirit of JCB and remove from our path the backstop that is the last Brussels-built blockage in the path of a global Britain".
Theresa May to deliver key Brexit speech at Stoke-on-Trent factory
Dismissing the EU's repeated insistence that it will not agree a deal without a backstop arrangement to protect the Irish border, Mr Johnson said: "Whatever our friends and partners are saying now, I think they will be flexible, because ... it's only in the last few days and weeks of a negotiation that the big concessions are really made.
"And with their economies stuttering a bit now, with the £95 billion surplus that they have with us in the UK on goods alone, I think they have every incentive to listen to us.
"We are already hearing positive noises from our German friends, so we must have the courage to ask and we must mean it this time."