Tory MPs are in talks with Labour to prevent Britain leaving the European Union without a deal, John McDonnell has suggested.
The shadow chancellor said Parliament can stop the Government taking the country out of the block without an agreement in place.
But Chris Grayling said the Labour MP was talking nonsense and accused him of threatening to create a chaotic Brexit.
The Transport Secretary insisted Britain would be successful even if it left without a deal and suggested crashing out would lead to British farmers growing more food to meet demand.
Former Brexit minister David Jones said Britain should suspend negotiations until the EU is prepared to talk sensibly about money and future trade terms.
Mr McDonnell claimed the Tories are fighting among themselves rather than negotiating with Brussels and said he was not willing to countenance a “no deal” outcome.
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He expects moves to guarantee in law a “meaningful vote” on the outcome of Brexit talks will secure a Commons majority.
The European Union (Withdrawal) Bill is notably absent from the Commons schedule for the week ahead, with the Government saying it wants to closely evaluate some 300 amendments and more than 50 new clauses proposed.
Mr McDonnell told BBC One’s Andrew Marr Show: “I don’t think there’s a majority for no deal. I think on a cross-party basis you’ll see in the debates in the coming week – the Government will get the message, there will be a deal.”
He added: “When we amend the legislation, which I think we will, I think there’s a majority to do that, to have a meaningful vote.”
Pressed on whether there had been talks with Tory MPs, Mr McDonnell replied: “There are discussions going right the way across the House.”
Mr Grayling said the shadow chancellor was “talking a lot of complete nonsense” because Parliament had already voted to leave the European Union.
Secretary of State for Transport Chris Grayling accused John McDonnell of threatening to create a chaotic Brexit (Peter Byrne/PA)
He told Marr: “John McDonnell threatening to derail this bill is John McDonnell threatening to create the kind of chaotic Brexit he himself is warning against.”
The Cabinet minister insisted Britain will “succeed whatever happens” but said it would be bad for the EU if no agreement was struck.
Asked what would happen to food prices if there was no deal, he said farmers would “grow more here” and “we’ll buy more from around the world”.
He told the programme: “It would mean that producers, supermarkets bought more at home, that British farmers produced more, that they bought more from around the world and it would damage French producers and continental producers.”
Shadow Brexit secretary Sir Keir Starmer said the exit bill should be kept as low as possible but suggested Labour would consider making payments to the EU after Brexit to gain access to the customs union.
He told ITV’s Peston On Sunday: “We’ll have to see subject to negotiations. Obviously, ideally no, or keep it low.
“It’s a very simple thing – if economically it’s better off to have an arrangement that works for our businesses and secures our economy then we would do it.”
Tory former minister Mr Jones said Britain should toughen up its negotiating strategy.
He told BBC Radio 4’s The World This Weekend: “If they are seeking a specific some of money, I can’t see for the life of me why it makes any difference at all to say ‘this is what we want’.
“The best way of dealing with the logjam is to say look, until such time as you will talk sensibly about money, and also about our future relationship, which of course is a matter that is related to it, we will suspend the negotiations.
“But, in the meantime, until such time as you talk to us we will assume you are not really serious and we will of course have to prepare for life outside the EU in which we will be trading with you on World Trade Organisation terms.”
Liberal Democrat Brexit spokesman Tom Brake said: “The Lib Dems will work with any party to stop a ‘no deal’ scenario and would vote against a ‘no deal’ outcome in Parliament.”
Foreign Secretary Boris Johnson held talks on European security with counterparts from eight countries, Bulgaria, Croatia, Czech Republic, Hungary, Poland, Romania, Slovakia and Slovenia, at grace and favour mansion Chevening House.
He said: “Our departure from the EU will make no difference to Britain’s unconditional and immovable commitment to the security and defence of Europe.
Foreign Secretary Boris Johnson at Chevening House with counterparts from eight European countries (Daniel Leal-Olivas via AP)
“This meeting was a further demonstration that the UK is a vital partner in the security of our continent.”