Donald Trump will this week hear prosecutors explain why his alleged cover-up of a hush money payment to a porn star during his 2016 campaign broke the law, at the first-ever criminal trial of a former US president.

Lawyers for the Republican presidential candidate will also make their opening statement in what may be the only one of Trump’s four criminal prosecutions to go to trial before his Nov 5 election rematch with Joe Biden.

Prosecutors say the $130,000 payment made by Mr Trump’s former lawyer Michael Cohen’s to porn star Stormy Daniels for her silence about an alleged sexual encounter with Trump a decade earlier deceived voters in the waning days of Trump’s 2016 campaign, when his candidacy was struggling with other revelations of sexual misbehaviour.

Trump has pleaded not guilty to 34 counts of falsification of business records brought by Alvin Bragg, the Manhattan district attorney, and denies having had a sexual encounter with Ms Daniels.

A colourful cast of witnesses will take the stand during the trial at the Lower Manhattan courthouse.

Here are some key figures set to testify in the case, which is expected to last six weeks:

The ex-publisher of the National Enquirer is expected to be the prosecution’s first witness on Monday.

The long-time friend of Mr Trump was the CEO of American Media, the tabloid’s parent company, until August 2020.

Prosecutors say Mr Pecker met with Mr Trump and his former lawyer Michael Cohen at Trump Tower in August 2015 to discuss using the National Enquirer to suppress negative stories about the presidential candidate.

The plan is alleged to have involved buying exclusive rights to the stories but not publishing them.

Prosecutors say the Stormy Daniels payment, which is the focus of the trial, was part of a broader “catch and kill” scheme to bury stories about Mr Trump.

Mr Pecker, 72, and American Media provided details about Mr Cohen’s payment to Ms Daniels after being subpoenaed by federal investigators in April 2018, according to prosecutors.

Mr Pecker was later granted immunity in exchange for testimony about Mr Trump’s knowledge of the payment.

The adult film actress, whose real name is Stephanie Clifford, claims she had a sexual encounter with Mr Trump in 2006 and was paid $130,000 by Mr Cohen for her silence ahead of the 2016 presidential election.

Mr Cohen says his former boss directed the payment. Prosecutors claim Mr Trump falsely classified reimbursements to Mr Cohen as legal expenses. The former president has pleaded not guilty to 34 felony counts of falsifying business records.

Ms Daniels, 45, claims the liaison took place in 2006, when she was 27 and Mr Trump, then the star of The Apprentice, was 60.

Mr Trump, now 77, has denied the encounter with Ms Daniels and said the payment was personal and not related to the campaign.

The star witness for the prosecution once vowed to “take a bullet” for the former president.

For a decade, Michael Cohen served as Mr Trump’s lawyer and backroom fixer, working, in his own words, to cover up his ex-boss’s “dirty deeds”.

It was Mr Cohen, 57, who facilitated, and was later jailed for, the hush money payment to Ms Daniels. But critics say a past conviction for lying to Congress undermines his credibility as a witness.

Mr Cohen paid Ms Daniels out of his own pocket through a shell company and arranged for her to sign a non-disclosure agreement, according to prosecutors.

In August 2018, Mr Cohen pleaded guilty to a campaign finance law violation for paying Ms Daniels.

He was sentenced to three years in prison for that and other crimes and served more than a year before being released.

The public relations executive, 35, served as Trump’s press secretary during his presidential campaign.

Once considered one of Donald Trump’s closest confidantes and most trusted aides, Ms Hicks later became his White House communications director.

Prosecutors will ask her to shed light on what was happening inside the political operation of the Trump campaign in the final weeks before the 2016 election.

A search warrant released in July 2019 indicated that Ms Hicks participated in phone calls between Mr Trump and Mr Cohen where they allegedly discussed the hush money payments in 2016.

The 45th US president has said he plans to testify at his historic criminal trial.

Many legal experts suggest it is a risky strategy as it opens him up to probing cross-examination by skilled prosecutors.

Defendants are presumed innocent and are not required to take the stand.

But prosecutors must prove Mr Trump intended to break the law to secure a conviction and his testimony could be important in rebutting that assertion.

Mr Trump frequently uses courtroom appearances to rally his supporters. The Republican candidate might want to take advantage of the media spotlight on his trial for the benefit of the 2024 election campaign.