Police in major US cities are preparing for potential unrest in case ex-President Donald Trump is arrested this week as part of a hush-money inquiry.
Authorities in New York, Washington DC and Los Angeles have ramped up their law enforcement presence.
A Manhattan prosecutor may charge Mr Trump over how he declared a payment to a porn star to keep quiet about an alleged affair.
It would be the first criminal case brought against a former US president.
Steel barricades were erected on Monday outside the prosecutor’s office and the Manhattan Criminal Court, where Mr Trump could be charged, fingerprinted and photographed if charges are filed this week, as US media widely anticipate.
Increased police presence and barricades have also been seen outside Manhattan’s Trump Tower.
Every member of the New York Police Department (NYPD), including plainclothes detectives, has been ordered to wear their full uniform on Tuesday and is being placed on standby to mobilise.
As of Tuesday morning, however, dozens of camera crews and reporters had taken over city sidewalks in the vicinity of the courthouse, outnumbering by far the handful of demonstrators who had shown up to voice their opinions on the potential indictment.
The NYPD and the FBI’s Joint Terrorism Task Force have been in touch with the US Secret Service, whose job it is to protect presidents and former presidents, about how a potential arrest might take place.
The Secret Service agents assigned to protect Mr Trump are expected to stay with him in the event of an arrest.
US media reports there will be no “perp walk” – when an arrested suspect is walked through a public place by officers, typically an opportunity for media to take photos and videos.
The US Capitol Police, who protect lawmakers on Capitol Hill in Washington DC, has deployed bike rack fencing around the perimeter of the Capitol complex and will beef up staffing.
The Capitol Police plan to issue an emergency declaration on Tuesday, a congressional source told CBS. The order aims to increase co-ordination with other law enforcement agencies.
More civil disturbance officers will also be on standby, though the congressional source said there was no specific threat and that the order was proactive.
In Los Angeles, the LAPD and federal officials were preparing for a pro-Trump protest on Tuesday outside a federal building, the LA Times newspaper reports.
US intelligence officials have detected an uptick in online threats against legal and government officials since Mr Trump wrote online on Saturday that he expected to be arrested on Tuesday.
Most of the threats were against Manhattan District Attorney Alvin Bragg, the man widely expected to file charges against Mr Trump.
On Saturday, the same day Mr Trump posted that his supporters should protest, Mr Bragg sent an email to staff.
“We do not tolerate attempts to intimidate our office or threaten the rule of law in New York,” the prosecutor wrote.
Mr Bragg’s case centres on a $130,000 payment from Mr Trump’s former lawyer, Michael Cohen, to porn star Stormy Daniels weeks before the 2016 presidential election to keep her quiet about an alleged affair with Mr Trump years earlier.
His office is evaluating how the former president reimbursed Cohen. The record for the payment describes it as “legal fees” and prosecutors could argue this amounts to Mr Trump falsifying business records.
That is a misdemeanour in New York, typically resolved with a fine. But legal analysts say it could be upgraded to a more serious felony charge, which carries prison time, if prosecutors argue the lie was used in order to violate campaign laws.
The former president denies any wrongdoing and says he never had an affair with Ms Daniels.
A grand jury was convened in January to determine whether there is enough evidence to indict Mr Trump.
On Monday, the grand jury heard from a Trump ally named Robert Costello who was called by the Trump team to undermine the prosecution’s star witness, Cohen.
Mr Costello told reporters after emerging from two hours of testimony: “I told the grand jury that this guy [Cohen] couldn’t tell the truth if you put a gun to his head.”
He claimed Cohen, whom he used to work with, had once told him that Mr Trump was not aware of the payment to Ms Daniels.
After Mr Costello’s testimony on Monday, Cohen hit back, saying that Mr Costello “lacks any sense of veracity”.
Cohen was jailed in 2018 for multiple offences including violating campaign finance laws by not declaring the payment to Ms Daniels. Mr Trump has said he only learned of the payment much later.
In a post on his Truth Social platform on Tuesday, Mr Trump said: “In the history of our Country there cannot have been a more damaged or less credible witness at trial than fully disbarred lawyer and felon, Michael Cohen.”
The jury is expected to hear from at least one more witness on Wednesday before any charges are filed.
Mr Trump has vowed to continue his campaign for the 2024 presidential nomination even if he is indicted.
But 44% of Republicans said he should drop out of the presidential race if charged, a Reuters/Ipsos poll found on Monday.