Barricades have been erected outside a New York court as the city prepares for the possibility Donald Trump could be arrested and charged over alleged hush money paid to porn star Stormy Daniels during his 2016 presidential campaign.
It would be the first criminal case brought against a former US president.
On Saturday, Mr Trump urged followers on social media to protest against what he said was his looming arrest.
It has raised fears of a repeat of violent scenes seen at Capitol Hill after his 2020 presidential defeat.
New York Mayor Eric Adams told reporters police were monitoring social media and keeping an eye out for “inappropriate actions” in the city.
The New York Police Department said there were no known credible threats.
However, barricades have been erected outside Trump Tower and Manhattan Criminal Court for crowds and any trouble following the former president’s claim his arrest is imminent.
If charged, Mr Trump would likely have to travel from his Florida home for fingerprinting and other processing.
Law enforcement officials met on Monday to discuss the logistics, several media outlets reported.
Mr Trump’s lawyer, Joseph Tacopina, told the Associated Press news agency that if the former president is indicted “we will follow the normal procedures”.
A grand jury, which heard further testimony on Monday, could bring charges as soon as this week.
Mr Trump, who is seeking the Republican nomination for the White House again in 2024, had predicted he would be arrested on Tuesday.
On Monday the grand jury heard from a witness, lawyer Robert Costello. He said Mr Trump’s former lawyer Michael Cohen had handled the hush-money payments without Mr Trump’s involvement.
“Michael Cohen decided on his own – that’s what he told us – on his own, to see if he could take care of this,” Mr Costello told reporters following his testimony, at Mr Trump’s legal team’s request.
Mr Cohen, who testified twice before the grand jury, has said publicly Mr Trump directed him to make the payments on his behalf.
The investigation by Manhattan District Attorney Alvin Bragg is one of several legal challenges Mr Trump faces, including legal action over the 6 January, 2021, Capitol riots.
Mr Bragg’s office has apparently been examining whether any state laws were broken in connection with the payments or the way Mr Trump’s company compensated Mr Cohen for his work to keep the women’s allegations quiet.
Mr Cohen pleaded guilty in 2018 to federal campaign finance violations tied to his arranging payments to Ms Daniels, whose legal name is Stephanie Clifford, and another woman in exchange for their silence about affairs they claimed with Mr Trump.
Mr Trump has denied any wrongdoing and that any such affairs took place.
Around 44% of Republicans say Mr Trump should drop out of the presidential race if he is indicted, according to a seven-day Reuters/Ipsos poll that concluded on Monday.