Several Labour figures say privately they believe that the prime minister ought to follow the example of Mark Carney, the Canadian prime minister, who warned in a speech at the World Economic Forum in Davos on Tuesday that the “old order is not coming back”.
He said: “Middle powers must act together because if we’re not at the table, we’re on the menu.”
Carney’s problems with the US are more acute than the UK’s.
In the moments before his post on Truth Social accusing Sir Keir of “stupidity”, Trump posted a map of the US which incorporated not only the US but Canada too, as well as Greenland and Venezuela.
Trump appearing to revive his threats towards Canada could pose particular problems for Sir Keir, too.
At the heart of Sir Keir’s strategy for handling Trump – a strategy which was seen until this week as one of the clearest triumphs of his time as prime minister – was the use of the Royal Family.
On his first visit to the Oval Office to meet Trump last year, Sir Keir whipped from his pocket a letter from the King extending an invitation to Trump for an unprecedented second state visit to the UK.
That has now happened but it does not seem to have secured permanent warm relations with Trump.
And the King is the King of Canada as well. What does the deterioration in US-Canadian relations mean for the expected visit of the King to the US this year to mark 250 years of its independence?
Even as his position toughened rhetorically today, those around Sir Keir remain resistant to pressure for him to deliver the full-throated ‘Love Actually moment’ some in Labour desire.
“You can have these fantasies about sticking it to world leaders,” one confidant of the PM said, “but you still have to speak to them the next day. What do you say then?”
It seems likely that Sir Keir’s rhetoric in PMQs will sate some Labour MPs for now.
But there was a warning from Steve Witherden, a backbencher from the left of the Labour Party, that there will be ongoing pressure for him to go further: Witherden urged retaliatory tariffs on the “thug in the White House” – an approach the prime minister is desperate to avoid.