Donald Trump, the former US president and front-runner for the 2024 Republican nomination, pleaded not guilty on Tuesday to 34 felony counts of falsifying business records after an investigation into hush money paid to a porn star.

Wearing a dark blue suit and red tie, Trump, 76, exhibited little emotion on his face when he waved to a crowd assembled outside the courthouse after he was driven in a motorcade from his New York residence at Trump Tower.

Trump sat with his hands folded as he entered his plea flanked by his lawyers.

"Not guilty," Trump said when asked how he pleaded.

He is the first sitting or former US president to face criminal charges.

Taken together, the charges carry a maximum sentence of 136 years in prison under New York law but an actual prison sentence if he is convicted at a trial would almost certainly be far less than that.

While falsifying business records in New York on its own is a misdemeanour punishable by no more than one year in prison, it is elevated to a felony punishable by up to four years in prison when done to advance or conceal another crime.

Trump, who has called the charges politically motivated, held his fist in the air in a gesture to reporters as he departed Trump Tower.

Looking sombre, Trump said nothing as he walked past police and through a hallway in the courthouse before entering the courtroom for the arraignment proceeding. A photo taken by a photographer in the courtroom authorised by the judge showed Trump sitting at the defence table, flanked by his lawyers.

Trump was indicted by a Manhattan grand jury last week in a case stemming from a 2016 hush-money payment to porn star Stormy Daniels, though the specific charges had yet to be disclosed.

From his motorcade, Trump posted on social media: "Heading to Lower Manhattan, the Courthouse. Seems so SURREAL - WOW, they are going to ARREST ME. Can't believe this is happening in America."

Trump was due to surrender to the office of Manhattan District Attorney Alvin Bragg before an arraignment proceeding before Justice Juan Merchan. At an arraignment, a defendant hears charges and can enter a plea. Trump was fingerprinted but no mugshot photo was taken, according to a Twitter post by a New York Times reporter.

In other social media posts ahead of the arraignment, Trump renewed his attacks on Merchan, who last year presided over a trial in which Trump's real estate company was convicted of tax fraud.

Trump, who served as president from 2017 to 2021, in November announced a bid to regain the presidency in 2024 in a bid to deny Democratic President Joe Biden, who beat him in 2020, a second term in the White House.

Trump's lawyers had urged the judge to block any videography, photography and radio coverage, arguing it would worsen "an already almost circus-like atmosphere."

The businessman-turned-politician has been a familiar figure for decades in New York, the city where he was raised, built his real estate business and became a celebrity.

On a cool and sunny early spring day in the most-populous US city, Trump supporters and detractors were separated by barricades set up by police to try to keep order, though there were some confrontations.

"Let's keep it civil, folks," a police officer told them.

Hundreds of Trump supporters, at a park across from the Manhattan courthouse, cheered and blew whistles, outnumbering his detractors. The Trump critics held signs including one of Trump dressed in a striped jail uniform behind bars and another that read, "Lock Him Up."

The White House remained mum on the drama in New York.

"I think the American people should feel reassured that when there is an ongoing case like this one that we're just not commenting," White House spokesperson Karine Jean-Pierre told reporters.

Any trial is at least more than a year away, legal experts said. Being indicted or even convicted does not legally prevent Trump from running for president.

Bragg, a Democrat who led the investigation, was set to give a news conference after the arraignment.

In a social media post, Trump said Manhattan Criminal Court was a "very unfair venue" and urged that the case be moved to the New York City borough of Staten Island, which regularly votes Republican.

Trump will return to Florida and deliver remarks from his Mar-a-Lago resort at 8:15 p.m. on Tuesday (0015 GMT on Wednesday), his office said.

Among the pro-Trump demonstrators was Gina Witcher, 55, of Maryland.

"We feel like this is a very scary indictment," Witcher said, accusing Democratic prosecutors of going after conservatives for political reasons.

New Jersey resident Susan Cerbo, 55, wore an American flag cowboy hat as she and her sister stood on the steps of a church across the street from Trump Tower holding a "Trump for President" banner.

"Honestly, he's just targeted because he's a presidential candidate," Cerbo said. "If you can do it to him with all his money and power, they can do it to any citizen of the United States."

Manhattan resident Kim Britt, 69, was among the anti-Trump demonstrators.

"If anyone is above the law, then we're not going to get anywhere," said Britt, holding a sign reading, "Tick Tock Time's Up!"

Trump's lead has widened over rivals in the Republican Party's presidential nominating contest, according to a Reuters/Ipsos poll released on Monday, conducted after news broke that he would face criminal charges.

Some 48 percent of Republicans say they want Trump to be their party's presidential nominee, up from 44 percent last month. Second-place Florida Governor Ron DeSantis fell from 30 percent to around 19 percent. More than two-thirds of poll respondents said they believed Trump paid hush money to Daniels, but half said the charges were politically motivated.

The Manhattan grand jury that indicted Trump heard evidence about a US$130,000 payment to Daniels in the waning days of the 2016 presidential campaign. Daniels has said she was paid to keep silent about a sexual encounter she had with Trump at a Lake Tahoe hotel in 2006.

Trump denies a sexual relationship but has acknowledged reimbursing his former personal lawyer Michael Cohen for the payment. In 2018, Cohen pleaded guilty to federal campaign finance law violations and was sentenced to three years in prison. He testified in the Manhattan investigation last month.

Trump faces a separate criminal probe by a Democratic local prosecutor in Georgia into whether he unlawfully tried to overturn his 2020 election defeat in the state. He also faces two US Justice Department investigations led by a special counsel into efforts to overturn the 2020 election results and his handling of classified documents after leaving office. (Reuters)