A New York grand jury investigating Donald Trump over a hush money payment to a porn star appears poised to complete its work soon as law enforcement officials make preparations for possible unrest in the event of an indictment.

Trump over the weekend claimed without any evidence that he would be arrested on Tuesday, with his representatives later saying he was citing media reports and leaks. There was no indication that prediction would come true, though the grand jury appeared to take an important step forward by hearing Monday from a witness favourable to Trump, presumably so prosecutors could ensure the panel had a chance to consider any testimony that could be remotely seen as exculpatory.