Manhattan prosecutors postponed without any explanation a scheduled grand jury session Wednesday in the investigation into Donald Trump over hush money payments during his 2016 presidential campaign, at least temporarily slowing a decision on whether to charge the ex-president.

The postponement was confirmed by four people familiar with the matter who spoke on condition of anonymity to The Associated Press because they were not authorized to discuss an ongoing investigation by name. It was not immediately clear why the proceedings were postponed, but the grand jurors were told to be on standby for Thursday, another day when the New York panel has been meeting in recent weeks.

When the grand jurors next meet, they may hear from yet another witness, according to a person familiar with proceedings that appear to be nearing a decisive vote on whether or not to indict Trump.

The panel has been probing Trump's involvement in a $130,000 payment made in 2016 to porn actor Stormy Daniels to keep her from going public about a sexual encounter she said she had with Trump years earlier. Trump has denied the claim, insisted he did nothing wrong and assailed the investigation, led by Manhattan District Attorney Alvin Bragg, as politically motivated.

Wednesday's abrupt development, which a person familiar with the matter said was not connected to security concerns, came amid growing anticipation that Trump could soon be charged. Grand jury proceedings are shrouded in secrecy, making it hard to predict with certainty what action might be taken and when.

As the panel has been hearing from final witnesses, Trump has contended his arrest is imminent and law enforcement officials have accelerated security preparations in the event of unrest accompanying an unprecedented charge against a former U.S. president.

The district attorney's office declined to comment on the postponement, which was earlier reported by Business Insider.

Prosecutors had recently invited Trump himself to appear before the grand jury, and on Monday heard from a witness favorable to his case as a way to ensure that the panel would be presented with any information that could conceivably be considered exculpatory.

Trump over the weekend stated that he expected to be arrested Tuesday, though the day came and went without that happening.

- MICHAEL R. SISAK and ERIC TUCKER Associated Press