WATCH: House Democrats’ montage of Capitol riot

A mob of Donald Trump supporters stormed the Capitol in Washington on Jan. 6. The former president's second impeachment trial began Tuesday. (Jason Andrew/The New York Times)

A mob of Donald Trump supporters stormed the Capitol in Washington on Jan. 6. The former president's second impeachment trial began Tuesday. (Jason Andrew/The New York Times)

Donald Trump’s historic second impeachment trial opened Tuesday in the Senate with graphic video of the deadly Jan. 6 attack on Congress and the defeated former president declaring, “We’re going to walk down to the Capitol!” as he encouraged a futile fight over his presidency.

The lead House prosecutor told senators the case would present “cold, hard facts” against Trump, who is charged with inciting the siege of the Capitol to overturn the election he lost to Democrat Joe Biden. Senators sitting as jurors, many who fled for safety that day, watched the jarring video that showed the chaotic scene, rioters pushing past police to storm the halls, Trump flags waving.

Watch the video below. Warning: Language may offend some viewers.

“That’s a high crime and misdemeanor,” said Rep. Jamie Raskin, D-Maryland, in opening remarks. “If that’s not an impeachable offense, then there’s no such thing.”

Trump is the first president to face impeachment charges after leaving office and the first to be impeached twice. The Capitol siege stunned the world as rioters stormed the building to try to stop the certification of Biden’s victory, a domestic attack on the nation’s seat of government unlike any in its history. Five people died.

Trump’s lawyers are insisting that he is not guilty of the sole charge of “incitement of insurrection,” his fiery words just a figure of speech as he encouraged a rally crowd to “fight like hell” for his presidency. But prosecutors say he “has no good defense” and they promise new evidence.

“Hear ye, hear ye, hear ye,” the acting sergeant at arms intoned to start the trial.

Security remains extremely tight at the Capitol, a changed place after the attack, fenced off with razor wire and armed National Guard troops on patrol. The nine House managers walked across the shuttered building to prosecute the case before the Senate.

In an opening prayer, Senate Chaplain Barry Black asked God to “take control of this impeachment trial” and “have mercy on our beloved land.”

With senators gathered as the court of impeachment, sworn to deliver “impartial justice,” the trial is starting with debate and a vote over whether it’s constitutionally permissible to prosecute Trump after he is no longer in the White House. First, senators voted on a resolution laying out the trial schedule for the days ahead.

Senate Majority Leader Chuck Schumer said it was the senators’ “solemn constitutional duty” to conduct a fair trial of “the gravest charges ever brought against a president.”

Presiding is not the chief justice of the Supreme Court, as has been tradition for the nation’s few presidential impeachment trials, but the chamber’s senior-most member of the majority party, Sen. Patrick Leahy of Vermont.

Acquittal is likely, but the trial will test the nation’s attitude toward Trump’s brand of presidential power, the Democrats’ resolve in pursuing him and the loyalty of Trump’s Republican allies defending him.

Trump’s defense team has embraced the question of constitutionality, which could resonate with Republicans eager to acquit Trump without being seen as condoning his behavior. They argue in filings the trial is “patently ridiculous.”

But the House prosecutors will cite the nation’s founders to declare a president “must answer comprehensively for his conduct in office from his first day in office through his last.” There is no “January exception” just before he leaves office, they will argue, according to aides granted anonymity to discuss the arguments ahead of the trial.

It appears unlikely that the House prosecutors will call witnesses, in part because the senators sworn as jurors, forced to flee for safety, will be presented with graphic videos recorded that day. At his Mar-a-Lago club in Florida, Trump has declined a request to testify.

Instead, House managers prosecuting the case will show videos of the violence, including never-before-seen evidence, and chart a story beginning with Trump’s claims the election was stolen and ending with the riot.

Trump’s defense team has said it plans to counter with its own cache of videos of Democratic politicians making fiery speeches. “We have some videos up our sleeve,” senior Trump adviser Jason Miller said on a podcast Monday.

White House press secretary Jen Psaki said Monday that Biden will be busy with the business of the presidency and won’t spend much time watching the televised proceedings. “He’ll leave it to his former colleagues in the Senate,” she said.

The Associated Press contributed to this report.