Venice, Italy - George Clooney has praised Joe Biden for being "selfless" by giving up power and pulling out of the 2024 presidential race.

The lifelong Democrat and Hollywood actor (62) called for 81-year-old Biden to step down amid the US president stumbling over his words when he faced Republican Donald Trump during a televised debate.

He wrote in a New York Times opinion piece in July that he loves Biden but the party would lose the presidential race as well as any control in Congress with him as the nominee.

"This isn't only my opinion; this is the opinion of every senator and congress member and governor that I've spoken with in private," Clooney said.

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When asked about this moment, at a press conference at the Venice International Film Festival on Sunday, he said: "I never had to answer that question, so I suppose I'll do it here.

"The person who should be applauded is the president who did the most selfless thing that anybody has done since [the first US president] George Washington, and that's true. And so … all the machinations that got us there … none of that's going to be remembered, and it shouldn't be.

"What should be remembered is the selfless act of someone who … it's very hard to let go of power, we know that, we've seen it, all around the world. For someone to say, 'I think there's a better way forward,' all the credit goes to him, and that's really the truth, and all the rest of it will be long gone and forgotten.

"So, I'm just very proud of where we are in the state of the world right now, which I think many people are surprised by, and I think we're all very excited for the future."

Vice President Kamala Harris has since stepped in as the Democrat nominee, and Clooney has backed her.

In Venice, he is promoting the movie Wolfs, about fixers forced to work together, alongside Brad Pitt.

Pitt's former partner Angelina Jolie, with whom he has six children, was at the film festival on Thursday to promote her new film, a biopic about the opera singer Maria Callas.

The details of their divorce, which was filed by Jolie in September 2016, have yet to be finalized.