New York, New York - The judge in Donald Trump's historic criminal trial on Tuesday warned the Republican presidential hopeful against intimidating jurors as seven panelists were chosen with unexpected speed following questioning by both sides.

There had been speculation that jury selection could take weeks in such a high-profile and sensitive case – the first criminal trial of a former US president, who also is running to return to the White House this November.

But Judge Juan Merchan ended the session saying he was hopeful opening arguments could begin as early as Monday.

After a preliminary phase in Trump's trial in which prospective jurors could opt out if they felt unable to be impartial or had extenuating circumstances, defense attorneys and prosecutors began questioning the candidates in depth.

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Twelve jurors in total are needed, and six alternates will also be chosen.

Merchan cautioned Trump at one point that his muttering was audible to one juror who faced scrutiny over social media posts.

"I will not have any jurors intimidated in this courtroom," Merchan said.

Trump (77) has been ordered by Merchan to be in court daily, putting a major hitch in his campaign plans.

"I should be right now in Pennsylvania and Florida – in many other states, North Carolina, Georgia – campaigning," Trump said in angry remarks outside the court. He called Merchan "Trump-hating."

Merchan has warned Trump against repeating his frequent past attempts to turn hearings into impromptu campaign appearances with outbursts at witnesses and staff, as well as tirades on social media.

The judge has already scheduled a hearing next week to consider whether Trump should be held in contempt for violating a partial gag order restricting him from attacking individuals connected to the case.

Illustrating the extraordinary tension, potential jurors have been told they will remain anonymous to the public throughout the proceedings. Merchan said this is to protect them from possible bribery or physical harm.

On Monday, more than half of the first batch of 96 candidates were excused after signaling they could not be impartial.

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Then, on Tuesday, prospective jurors were grilled on their media consumption, political donations, and education.

A young Black woman in the pool of candidates said that, as a person of color, she has friends with strong opinions on Trump.

"You can't judge him because he speaks his mind," said another.

A third possible juror said he found Trump "fascinating and mysterious," prompting Trump's lawyer, Todd Blanche, to respond, "Umm, alright. Thank you."

Trump appeared to eye those in the jury box as they each answered 'yes' to a prosecutor's question about whether they would be able to return a guilty verdict. Candidates were then asked individually about social media posts.

In his New York case, the Republican is accused of falsifying business records while covering up an alleged extramarital sexual encounter with adult film actress Stormy Daniels to shield his first election campaign in 2016 from last-minute upheaval. If convicted, Trump would potentially face prison, but legal observers say fines would be more likely.

Trump faces three other criminal cases centered on his possession of top-secret documents after leaving office and his unprecedented attempts to overturn his 2020 election loss to Biden.