New York, New York - Donald Trump becomes the first US ex-president to go on criminal trial Monday – pushing the nation's legal and electoral systems to the limit less than seven months before Americans decide whether to return the scandal-plagued Republican to the White House.

Trump is accused of falsifying business records in a scheme to cover up an alleged sexual encounter with porn star Stormy Daniels so as not to doom his 2016 election.

The so-called hush money affair is only one of the four criminal cases hanging over Trump and arguably the least serious.

But the real prospect of Trump becoming a convicted felon – and potentially facing jail time – throws an astonishing wild card into an already unprecedented election in which the right-wing populist is running on dark vows of "vengeance" against Democratic President Joe Biden, who beat him in 2020.

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The trial will start with what could be a lengthy and contentious process to select 12 jurors.

Judge Juan Merchan will convene a pool of more than 100 ordinary citizens who must answer a questionnaire including checks on whether they have been members of far-right groups, like the Proud Boys, which led a mob of Trump supporters in the January 6, 2021, assault on the Capitol to stop certification of Biden's election.

The actual charges, however, revolve around the nitty gritty of finance laws.

Trump is accused of illegally covering up remittances to his longtime attorney and fixer, Michael Cohen, who was using the funds to pay Stormy Daniels to keep quiet about the alleged sexual encounter in the final weeks of the 2016 election campaign.

A New York grand jury indicted Trump in March 2023 over the payments made to Daniels, whose real name is Stephanie Clifford, with the ex-president charged with 34 counts of falsifying business records.

He denies the charges and could use the trial, scheduled for up to two months, as a prominent platform to decry what he alleges is "lawfare" and election interference by his political opponents. Trump also claims that he will not get a fair trial in heavily Democratic New York.

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However, the real estate magnate and longtime reality TV show star is using the limelight as an unlikely campaign boost – touting himself as a victim and using outrage among his supporters to fundraise.

Even if convicted, he would be able to appeal and would not be barred from continuing to run or even being elected president on November 5.

Trump's other three criminal cases – centered on his alleged hoarding of top-secret documents in Florida after he left the White House and his involvement in attempts to overturn the 2020 election – all face multiple delays.

In the New York case, Trump has repeatedly failed to secure meaningful delays and Merchan has signaled he will run the trial with a firm hand.

Last week, the judge extended an existing gag order, in place to prevent Trump from attacking those involved in the trial, widening it to cover family members of the judge and Manhattan District Attorney Alvin Bragg, the lead prosecutor.

The expansion of the order came after Trump lashed out at Merchan and his daughter in a series of posts on Truth Social.

"The stakes are very high. Because Trump and his counsel have succeeded so far in kicking down the road the federal documents and election interference cases," said University of Richmond law professor Carl Tobias. "The hush money case may be the only case that is tried prior to the November federal elections."

In New York, where Trump has been a fixture for decades as an entrepreneur, celebrity playboy, politician, and now criminal defendant, there is little sympathy.

"I don't know if he'll get a fair trial, but whatever happens... he did it to himself," said city resident Alberto Vasquez (45).