Trump and his allies push a false account of what the judge told jurors.

It was a shocking assertion for anyone with even a passing knowledge of American jurisprudence: The judge overseeing the trial of Donald J. Trump had said that jurors could individually choose from a menu of different crimes to find the former president guilty, so long as the total of votes added up to 12.

It was also untrue.

The suggestion — made in an online post by the Fox News anchor John Roberts — nonetheless found an immediate and massive audience, with some 5.7 million views on X, formerly known as Twitter. Surrogates and allies of Mr. Trump quickly amplified its arguments, as did Mr. Trump himself.