It may seem crass for Donald Trump to be using the New Orleans terrorist attack to score political points, but he knows, like every successful politician, that you should never let a good crisis go to waste.

No sooner had Fox News claimed that suspect Shamsud-Din Bahar Jabbar had entered the country through the Texas border two days ago than Donald Trump Jr had tweeted: “Biden’s parting gift to America – migrant terrorists.”

Over on Truth Social, the platform favoured by the president-elect, Mr Trump repeated his previous claim that “the criminals coming in are far worse than the criminals we have in our country”, which he said had been denied by the “fake news media” but had “turned out to be true”.

Democrats will, of course, condemn Mr Trump for shameless opportunism, but they will also know that his comments will cut through with the voting public in America.

As it happens, the Fox News claim about crossing the border turned out to be unsubstantiated. According to investigators, Jabbar was a US citizen, but for many Americans that will be an irrelevant detail now.

Once again, Mr Trump has proved a master of controlling the narrative, however distasteful that may be, and support for his pledge to deport all undocumented migrants has just been turned up a notch.