New York, New York - Actor Robert De Niro on Tuesday spoke outside the New York court where Donald Trump is standing trial, branding him a dangerous "clown" who will become a dictator for life if re-elected.

The 80-year-old star, a longtime political activist and critic of Trump, has taken a growing role in the campaign to reelect Joe Biden, including starring in a new hard-hitting TV ad for the Democratic Party.

"When Trump ran in 2016, it was like a joke," DeNiro told reporters, calling the former president a "clown" and a "tyrant."

"We have a second chance, and no one is laughing now. This is the time to stop him."

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Trump has spoken daily to TV news cameras inside the court premises, claiming the trial is a political attack against him, lambasting the judge as biased and repeating falsehoods about the last election being rigged.

De Niro's unexpected press conference – against a noisy backdrop of pro-Trump protesters and car alarms -- appeared to be an effort to push back against Trump's dominance of the TV news channels.

"If he gets in. I can tell you right now, he will never leave," De Niro said. "Is that the country we want to live in? Do we want him running this country and saying, 'I'm not leaving? I'm dictator for life'?"

"The only way to preserve our freedoms and hold on to our humanity is to vote for Joe Biden for president," the legendary actor said.

Closing arguments began Tuesday in Trump's hush money trial, less than six months before the election.