New York (CNN Business) Robert De Niro says he thinks Democrats had no choice but to open an impeachment inquiry into President Donald Trump.

"It has to happen," De Niro told CNN Business' Brian Stelter on "Reliable Sources" Sunday. He called the present political situation a crisis, "and too many people are too gentle and genteel about it. And we're in a crisis situation, period," De Niro said. Two days earlier, on the red carpet for the New York Film Festival opening night premiere of his new film "The Irishman ," De Niro told Variety he hopes Trump gets impeached.

House Speaker Nancy Pelosi last week announced a formal impeachment inquiry into Trump after a whistleblower said the president had pressured Ukraine's leader to investigate the son of Democratic presidential candidate Joe Biden.

De Niro has become an outspoken Trump critic in recent years, and last year played Special Counsel Robert Mueller in a series of "Saturday Night Live" sketches about the White House. But as for whether Trump should step down as President, as the Connecticut Post suggested he do this week, the legendary actor is not so sure that will happen.

"I don't think he's capable of resigning," De Niro told Stelter. "He will say it's rigged or this or that. The day after he was elected, I said, well, give him a chance. You never know. You will see. But he is the — he's worse than I ever could have imagined."

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