Boris Johnson refused tonight to guarantee that he would back Rishi Sunak’s deal on the Northern Ireland Protocol in a warning to the Prime Minister.
The government is currently engaged in ‘intensive’ talks with the EU to resolve the bitter dispute over post-Brexit trade deals for Northern Ireland.
But despite suggestions that a deal could be reached this week, hopes of an imminent breakthrough have since faded.
Both the DUP and Tory Brexiters are withholding their support for a Protocol deal until they can take a closer look at a legal text.
And there is likely to be more alarm in Downing Street tonight after Johnson failed to say whether he would support a deal overseen by Sunak.
He urged Sunak to focus his efforts instead on controversial new Westminster laws that would give ministers the power to unilaterally annul parts of the Protocol.
Johnson’s intervention will add to nervousness among Sunak’s allies that the former prime minister could still lead a Conservative revolt over a Protocol deal.
Boris Johnson did not say whether he would support a Protocol deal overseen by Rishi Sunak

Northern Ireland Secretary Chris Heaton-Harris held further talks on the Protocol with the EU’s Maros Sefcovic this afternoon.
“It’s important that we wait and see what there might be,” Mr Johnson told Sky News tonight of Mr Sunak’s efforts to reach a Protocol resolution with Brussels.
“But I think the best way forward, as I said when I was running the government, is the Northern Ireland bill which passed comfortably in the House of Commons, I think without amendment, when I was in office just a few months.
“So I think that’s the best way forward.”
Pressed on whether he could guarantee his support for a Protocol deal reached by Sunak, Johnson added: “I think the best thing to do is to continue with the Northern Ireland bill that we agreed to.
‘It’s a very good bill, it solves all the problems, it solves the problems we have in the Irish Sea, it solves the paperwork problems, VAT and so on.
It is an excellent bill and it does not create any further problems in the economy of the whole island of Ireland. I would stick with that one.
Johnson agreed to the Protocol with the EU when he was prime minister. But he later turned against the deal he reached and criticized the EU’s “bureaucratic” implementation of post-Brexit trade rules.
A subsequent spat led to Johnson proposing the Northern Ireland Protocol Bill, which increased tensions with Brussels and angered moderate Conservatives who claimed the legislation would violate international law.
Earlier today Northern Ireland Secretary Chris Heaton-Harris traveled to Brussels for his latest talks with the EU’s Maros Sefcovic on the Protocol.
He described it as ‘another constructive meeting’ and said ‘intensive work continues’.
Sefcovic said that the two parties “will continue to engage in the outstanding issues related to the Protocol.”
It has been suggested that Mr Sunak is willing to drop the Northern Ireland Protocol Bill, which is currently stalled in Parliament, should he reach an agreement with the EU.
But Johnson’s comments add to increased pressure on the prime minister, including from within his own cabinet, to keep alive the threat of unilateral UK action on the Protocol.
Home Secretary Suella Braverman this week described the Northern Ireland Protocol Bill as “one of the biggest tools we have to solve the problem in the Irish Sea.”
He also warned that he would oppose any deal with the EU that would give him a “foothold” in Northern Ireland.
Ms Braverman said she was not prepared to resign over the issue, but told GB News last night: ‘I have taken a very direct position in the past because I have found the terms of previous deals intolerable.
“I do not support selling Northern Ireland and allowing the EU to gain a foothold in the UK.
“It is absolutely vital that we protect what we have won with the Brexit vote, that we move forward as a UK where the integrity of our Union is safeguarded and we properly regain control.
I know the Prime Minister shares that goal.

Home Secretary Suella Braverman said she would oppose any deal with the EU that would give it a “foothold” in Northern Ireland.

The prime minister had expected to present the new deal with the EU this week after flying to Northern Ireland to brief political leaders last Friday.

Ms Braverman downplayed the possibility that she might resign over the Protocol, saying she believed Mr Sunak shares her goals.
A government source said there was now a ‘99.9 per cent’ chance negotiations would go ahead next week as the prime minister tries to quell a backlash from the DUP and his own parliamentarians.
In her interview, Ms Braverman said the government was committed to working with the DUP, who refuse to return to sharing power in the Stormont Assembly unless there is a fundamental change to the Protocol.
‘We have always worked very closely with the DUP. they are trade unionists. They speak on behalf of a significant part of the Northern Ireland community and they need to be around the table,” he said.
“Ultimately, Stormont will only work if the DUP supports some proposal.”
During yesterday’s clashes in the House of Commons, the prime minister insisted that he would be “decisive” in defense of UK interests.
He told MPs: ‘I am a Conservative, a Brexiteer and a Unionist, and any deal we reach needs to tick all three boxes.
‘It needs to ensure Northern Ireland’s sovereignty, safeguard Northern Ireland’s place in our union, and it needs to find practical solutions to the problems facing people and businesses.
“I will be determined to fight for what is best for Northern Ireland and the UK.”

DUP leader Sir Jeffrey Donaldson welcomed the prime minister’s move but warned that any new deal must not involve “playing on the edges”.
But, in an ominous sign, DUP leader Sir Jeffrey Donaldson has warned that there would have to be significant changes to the Brexit deal with the EU, including an end to the ‘unacceptable’ situation that leaves Northern Ireland governed by the laws trade unions in the EU over which it has no say.
Sir Jeffrey welcomed the prime minister’s move but cautioned that any new deal must not involve “tinkering”.
Former Brexit minister Lord Frost said: “We have learned that we cannot rely on EU commitments that are not tied to or rest on good faith or reasonable action by the EU.” They must be legally clear and enforceable. If not, we’ll be back here before too long.