WASHINGTON (AP) — Donald Trump’s historic second impeachment trial has opened in the Senate with graphic video of the deadly Jan. 6 attack on Congress after the defeated former president whips up a rally crowd.

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He shouts that “we're going to walk down to the Capitol” as he encourages a futile fight over his loss to Democrat Joe Biden.

Trump is charged by the House with inciting the violent mob attack on the U.S. Capitol to overturn the election.

Prosecutors argue Trump committed a “grievous constitutional crime," but his defense team insists his fiery words at the rally were just figures of speech.

His lawyers also say that trying a former president is unconstitutional.

The debate over that constitutional question is expected to highlight the opening day.

PHOTOS: Scene at U.S. Capitol shows chaos and violence