Former US president Donald Trump has said he expects to be “arrested” on Tuesday over hush money allegedly paid to a porn star before the 2016 election, calling on his supporters to protest.

With signs mounting that prosecutors are moving closer to indicting Trump, the 76-year-old billionaire took to his Truth Social platform on Saturday morning, saying: “Leading Republican candidate and former president of the United States of America will be arrested on Tuesday of next week. Protest, take our nation back!”

Trump chose to use his own social media platform to make the announcement, despite being reinstated on Facebook and YouTube on Friday, more than two years after he was banned over the US Capitol riot.

The indictment would make Trump the first former US president to be charged with a crime and would send political shock waves as he tries to secure the Republican nomination for the 2024 presidential election.

Already, Republican House Speaker Kevin McCarthy reacted with fury, accusing New York prosecutors of pursuing “political vengeance” against Trump and saying he would launch a congressional probe of the matter.

The investigation led by Manhattan district attorney Alvin Bragg, an elected Democrat, centres on $130,000 paid weeks before the 2016 polls to stop Stormy Daniels, whose real name is Stephanie Clifford, from going public about an affair she says she had with Trump years earlier.

Trump’s lawyer told CNBC on Friday evening that his client would surrender to face criminal charges if he was indicted.

Trump has denied having an affair with Daniels and has dismissed the investigation as politically motivated.

Illegal leaks

In his Truth Social post, written in capital letters, Trump referred to “illegal leaks from a corrupt and highly political Manhattan district attorney’s office” and said the investigation was “based on an old & fully debunked (by numerous other prosecutors!) fairytale.”

Hours later, Trump doubled down in another all-caps post, assailing his successor as “crooked” and urging his followers to “Protest, Protest, Protest!!!”

Trump’s lawyer Susan Necheles indicated that his posts were based on media reports and not on any fresh action taken by prosecutors.

“Since this is a political prosecution, the District Attorney’s office has engaged in a practice of leaking everything to the press, rather than communicating with president Trump’s attorneys as would be done in a normal case,” Necheles said in a statement to AFP.

A grand jury in New York, a citizen panel that examines the evidence presented by prosecutors to decide if a charge is warranted, has been hearing from witnesses in Trump’s case.

On Monday, jurors heard from Trump’s former lawyer and fixer Michael Cohen, who made the payment to Daniels. Cohen was sentenced to three years in prison in 2018 on federal charges related to the payment. He pleaded guilty but said he had been carrying out Trump’s orders.

Daniels herself met with prosecutors on Wednesday and “agreed to make herself available as a witness, or for further inquiry if needed”, according to her lawyer Charles Brewster.

Trump has also received an invitation to testify, which legal experts say is a sign that an indictment is near.

The payment to Daniels, if not properly accounted for, could result in a misdemeanour charge related to falsifying business records. That might be raised to a felony if the false accounting was intended to cover up a second crime, such as a campaign finance violation, The New York Times has reported.

2024 prospects

Trump is facing several criminal probes at the state and federal level over possible wrongdoing before, during, and after his term in office that threaten his new run at the White House.

In Georgia, a prosecutor is investigating Trump and his allies’ efforts to overturn his 2020 election loss in the southern state. The grand jury, in that case, has recommended multiple indictments, the forewoman revealed last month.

The former president is also the subject of a federal probe into his handling of classified documents as well as his possible involvement on the January 6, 2021, assault on the US Capitol.

Facebook and YouTube, where Trump has millions of followers, benched him days after the attack, arguing that his posts incited unrest.

Some observers believe an indictment bodes ill for Trump’s 2024 chances, while others speculate that it could on the contrary serve as a huge boost.

“The arrest secures the nomination for Donald Trump,” tweeted Rick Wilson, a political strategist who quit the Republican Party in protest over Trump. “The base will rally politically, and possibly physically. (Let me know how that goes.)”

Tech billionaire Elon Musk, a self-described libertarian who has increasingly aligned with Republican positions and who overturned the Twitter ban on Trump in the name of free speech, went even further.

“If this happens, Trump will be re-elected in a landslide victory,” Musk said in a tweet.

Trump called a new campaign rally in Texas on March 25.