New York, New York - Jurors began deliberating Wednesday on whether to convict Donald Trump in the first criminal trial of a former US president – with their decision potentially upending November's election, in which the Republican seeks to return to power.

After weeks of testimony from more than 20 witnesses, the piercing glare of the legal spotlight shifted to the 12-strong New York jury, kept anonymous for their own protection amid soaring political tensions.

After receiving final instructions from the judge, jurors left the courtroom to sit in a designated room where they alone would have the final say on 77-year-old Trump.

"You must set aside any personal opinions you have in favor or against the defendant," said Judge Juan Merchan.

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"As a juror, you are asked to make a very important decision about another member of the community."

No time limit is placed on the deliberations, but an acquittal or conviction would require unanimity. If just one juror refuses to join the others, the judge would have to declare a mistrial.

Trump is accused of falsifying business records to reimburse a $130,000 payment to silence adult film star Stormy Daniels when her account of an alleged sexual encounter could have imperiled his 2016 presidential campaign. Prosecutors say the fraud was motivated by a plot to prevent voters from knowing about his behavior.

If Trump is found guilty, the political repercussions would far outweigh the seriousness of the charges as, barely five months before the November 5 presidential election, the candidate would also become a convicted criminal.

The judge instructed Trump that he would have to remain in the courthouse while awaiting the verdict. Trump responded by stepping outside the courtroom to launch an angry statement to journalists, calling it a "very disgraceful situation."

"These charges are rigged," Trump said, claiming that "Mother Teresa could not beat these charges."

In closing arguments on Tuesday, Trump's defense team insisted the evidence for a conviction simply did not exist, while the prosecution countered that it was voluminous and inescapable.

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"The defendant's intent to defraud could not be any clearer," said prosecutor Joshua Steinglass, urging the jurors to use their "common sense" and return a guilty verdict.

If convicted, Trump faces up to four years in prison on each of 34 counts, but legal experts say that as a first-time offender, he is unlikely to get jail time.

A conviction would not bar him from the November ballot, and he would almost certainly appeal. In the case of a mistrial, prosecutors could seek a new trial.

Trump has been required to attend every day of the trial. However, he has used his trips to court and the huge media presence to spread his claim that the trial is a Democratic ploy to keep him off the campaign trail.

Polls show Trump neck and neck against President Joe Biden, and the verdict will inflame passions as the White House race intensifies.