Boris Johnson would "fail on the only promise" he made at the last election if the UK crashes out of the European Union without agreeing a trade deal, Sir Keir Starmer has said.
The Labour leader, using the Prime Minister's own words against him, said collapsing the negotiations with Brussels after promising to "get Brexit done" at the 2019 election would represent a "complete failure of statecraft".
During a visit to Dublin in September 2019 as he was working to secure a Withdrawal Agreement, Mr Johnson said no deal would be a failure of statecraft "for which we would all be responsible".
But speaking during a trip to the North East on Friday, the Prime Minister said it was "very, very likely" that the UK would leave the transitional trading arrangements with the EU on December 31 without an agreement.
The UK and EU have agreed that a firm decision on the future of the talks must be made on Sunday.
Sir Keir has criticised the Conservative Party leader for attempting to "dress up" no deal as an Australian-style arrangement – Downing Street shorthand for reverting to World Trade Organisation (WTO) rules with the UK's largest trading partner – under which Britain could prosper.
"It is a complete failure of statecraft, particularly from a PM who told us there was absolutely no chance of a no-deal Brexit," the former director of public prosecutions told the Mirror.
"There's no point dressing it up as an Australian deal. You might as well call it a Mongolian deal.
"It is no deal and if we end up there that means we haven't got a trading agreement with our most important trading partners.
"This is the PM who made one promise to the British people going into that election, that he would get Brexit done.
"It looks like he's going to fail on the only promise he has made to the British people."
Sir Keir, who is self-isolating until Tuesday after a staff member tested positive for coronavirus, also gave further indication that Labour would back any fresh terms agreed by the Government.
According to reports, the issue of whether Labour should vote for a deal or abstain in the Commons has caused a split at the top of the party.
The ex-shadow Brexit secretary said: "We haven't got a deal yet... But if it is a straight choice between a deal and no deal then I'm in no doubt that a deal is in the national interest."