Donald Trump turned himself in Tuesday for a historic New York court hearing held amid tight security and a global media frenzy, as the Republican billionaire becomes the first American president in history to face criminal charges.

In a spectacle playing out on live television - with rival protesters rallying outside -- the hearing marks a watershed moment for the US criminal and political system, with the potential to upend the 2024 White House race in which Trump is currently the presumptive Republican nominee.

The 76-year-old is expected to plead not guilty to a host of charges related to hush money paid to a porn star ahead of the 2016 election that brought him to power.

"Seems so SURREAL -- WOW, they are going to ARREST ME," Trump posted on his Truth Social app as he headed to the courthouse from Trump Tower, where he spent the night after flying from Florida.

"Can't believe this is happening in America. MAGA!"

The twice-impeached Republican is the first sitting or former American president to be criminally indicted -- a development that has propelled the United States into uncharted political waters.

Police lined the streets while helicopters buzzed in the skies as Trump's motorcade made the short drive to court, carried live on US networks although cameras will not be allowed for the hearing itself.

Trump waved at supporters after leaving his car before walking into the complex under US Secret Service protection. He was not subjected to a "perp walk" -- in which a defendant is escorted in handcuffs past media cameras.

The former president was due to undergo the standard booking procedure of being fingerprinted -- and potentially photographed, which would result in an all-time famous mug shot -- at the Manhattan District Attorney's office.

He will then learn at his arraignment, scheduled to start at 2:15 pm (1615 GMT) precisely what charges he faces. Trump was due to plead not guilty to all counts, his lawyers have said.

Protests outside court

Trump claims he is the victim of "political persecution" -- but is also using the court case to energize his support base and raise millions of dollars for his bid to reclaim the White House next year.

He plans to speak to reporters as he walks through the hallways toward court, one of his attorneys told CNN.

"THE RADICAL LEFT DEMOCRATS HAVE CRIMINALIZED THE JUSTICE SYSTEM," Trump wrote on Truth Social hours before the hearing, branding the legal proceedings a "kangaroo court."

Hundreds of people gathered outside the venue, including dozens of Trump supporters and anti-Trump demonstrators, media and curious onlookers.

Police stepped into the fray as the pro-Trump side -- many sporting "MAGA" hats and attire emblazoned with the American flag -- yelled slurs at counterprotesters.

The anti-Trump camp unfurled a large banner reading "Trump lies all the time" and chanted "Lock him up!" as Trump fans waved a flag with the slogan "Trump or Death."

About 30 counts, including at least one felony, are expected to be unsealed during the arraignment, which may last around 15 minutes.

Afterward, Trump is due to return straight to Florida, where he plans to deliver an evening speech.

$130,000 payment

Trump was indicted last week by a grand jury in the case brought by Manhattan District Attorney Alvin Bragg, an elected Democrat.

The charges revolve around the investigation of $130,000 paid to adult film actress Stormy Daniels just days before Trump's election win.

Trump's former lawyer and aide Michael Cohen, who has since turned against his ex-boss, says he arranged the payment to Daniels in exchange for her silence about a tryst she says she had with Trump in 2006.

Trump, whose third wife Melania had recently given birth at the time, denies the affair.

Legal experts have suggested that if not properly accounted for, the payment could result in charges for falsifying business records, possibly for the purpose of covering up a campaign finance violation.

Trump is facing a series of separate criminal investigations at the state and federal level that could result in further -- more serious -- charges between now and election day.

They include his efforts to overturn his 2020 election loss in the state of Georgia, his handling of classified documents, and his possible involvement in the storming of the US Capitol on January 6, 2021.

President Joe Biden, mindful that anything he might say could fuel Trump's claim of a politically "weaponized" judicial system, is one of the few Democrats holding back over the indictment of his rival.

Asked Monday whether he had faith in the legal system, Biden simply replied, "Yes."

But Republicans have largely rallied around Trump, including his rival in the party's presidential primary, Florida Governor Ron DeSantis, who called the indictment "un-American."