New York, New York - Jurors completed opening deliberations Wednesday on whether to convict Donald Trump in the first criminal trial of a former US president.

The 12-strong New York jury huddled for almost five hours before the judge sent them home for the night, ready to resume on Thursday.

Jurors – whose identities have been kept anonymous for their own safety – worked in a separate room, leaving 77-year-old Trump and the rest of the court to wait and guess at any developments.

Before being dismissed, the jury asked to reexamine testimony from two witnesses and also to hear again the judge's instructions on how to interpret the law.

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After weeks of testimony from more than 20 witnesses, the piercing glare of the legal spotlight is now entirely on the dozen ordinary New Yorkers.

"You must set aside any personal opinions you have in favor or against the defendant," said Judge Juan Merchan, before sending them to their work.

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 in order 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.

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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."