Theresa May and Boris Johnson are set for an awkward reunion in New York, as both attend the United Nations General Assembly following days of headlines about government infighting over Brexit.
The Prime Minister flew in late on Monday evening after a visit to Canada during which she was forced to fight off claims that Mr Johnson had become a "back-seat driver" in her Cabinet.
After the Foreign Secretary published a 4,000-word personal vision for Brexit, Mrs May attempted to stamp her authority on the situation with a firm declaration: "This government is driven from the front."
But a defiant Mr Johnson took to the airwaves from New York to restate his demand that there should be no extended "transition" period after Britain leaves the EU and that the UK should not have to make "extortionate" payments to Brussels for continued access to European markets.
Mr Johnson also side-stepped a question on whether he would resign if he did not get his way, saying: "You are barking slightly up the wrong tree here."
Officials said the pair had no formal meeting scheduled on Tuesday, but they are both expected to attend a reception for Commonwealth leaders in the evening.
The Foreign Secretary's repeated interventions have dominated the run-up to a crucial Brexit speech being delivered by Mrs May in Italy on Friday. Billed as the PM's most important update to the Government's position since her Lancaster House address in January, the Florence speech is thought likely to include an attempt to break the deadlock over the UK's financial settlement.
Speculation has been mounting she will offer to pay tens of billions of pounds to the EU during a two to three-year transition deal after the UK's formal exit in 2019.
Unconfirmed reports suggest a rift in the Cabinet between ministers such as Chancellor Philip Hammond favouring an "EEA-minus" Brexit involving Swiss-style payments for continued participation in the single market and those like Mr Johnson and Michael Gove who prefer a "Ceta-plus" deal involving a free trade agreement similar to that enjoyed by Canada.
Speaking in Ottawa following talks with prime minister Justin Trudeau on Monday, Mrs May dismissed this "binary" choice, insisting that as the first major country to leave the EU, the UK is in a "unique" position to forge its own tailor-made deal.
Former foreign secretary William Hague used an article in the Daily Telegraph to warn that senior ministers "lack co-ordination" on Brexit and it is "high time" that they settled on an agreed plan.
If Mrs May's crunch speech fails to unite the Cabinet, "Jeremy Corbyn will be prime minister", warned Lord Hague.
The Prime Minister attempted to take control of the Brexit process by moving chief negotiator Olly Robbins out of David Davis's Department for Exiting the EU to a new position where he will report directly to her.
As she flew to Canada on board her RAF jet, Mrs May insisted the Cabinet was fully united behind her approach to the Brexit talks.
"This government is driven from the front and we are all going to the same destination, because we are all agreed on the basis of the Lancaster House speech," she said.
For his part, the Foreign Secretary said he accepted that Mrs May was in charge of the negotiations while playing down suggestions that he was at odds with Mr Hammond and Mr Davis. He said that his article had been intended as an "opening drum roll" to Mrs May's Florence speech.
"There is one driver in this car. It's Theresa. What I am trying to do is sketch out what I think is the incredible exciting landscape of the destination ahead," said Mr Johnson. "Let's not try and find rows when there really aren't rows. I think it is a good thing to have a bit of an opening drum roll about what this country can do."
He made clear, however, that he stood by his arguments over the transition period.
"It is pretty important that it shouldn't be too long," he said. "We certainly don't want to be paying in extortionate sums for access to the single market. They wouldn't pay for access to our market."
Meanwhile, Dominic Cummings, the former Vote Leave director seen as an ally of Mr Johnson, launched a blistering attack on Mr Davis's handling of the negotiations.
In a series of tweets, he said the decision to begin the Article 50 withdrawal process before the Government was ready had been like "putting a gun in mouth and kaboom".
"The shambles now unfolding is a direct consequence of that historic unforgivable blunder," he wrote.
Mrs May will hold one-one-one talks a number of international leaders at the UN on Tuesday as part of her drive to promote "global Britain", as well as leading a session devoted to tackling the problem of modern slavery.