WASHINGTON — Federal prosecutors are expected to outline their case Thursday against former Proud Boys leader Enrique Tarrio and four lieutenants, who are charged with seditious conspiracy in one of the most consequential cases to emerge from the Capitol riot.

Opening statements in federal court would come just more than two years after Proud Boys members stormed the Capitol on Jan. 6, 2021, as part of what prosecutors say was a desperate plot to keep Democrat Joe Biden out of the White House after he defeated President Donald Trump in the 2020 election.

The trial is another huge test for the Justice Department, which recently secured the seditious conspiracy convictions of two leaders of another extremist group, the Oath Keepers. Tarrio is one of the most high-profile defendants in the sprawling Jan. 6 prosecution and the trial will provide an in-depth look at the far-right group that remains a force in mainstream Republican circles.

The department has charged nearly 1,000 people across the United States and its Jan. 6 investigation continues to grow.

It’s the first major trial to begin since the House committee investigating the insurrection urged the department to bring criminal charges against former President Donald Trump and associates who were behind his efforts to overturn his 2020 election loss.

While the criminal referral has no real legal standing, it adds to political pressure already on Attorney General Merrick Garland and Jack Smith, the special counsel he appointed who is conducting an investigation into Jan. 6 and Trump’s actions.

Jury selection in the case took two weeks as a slew of potential jurors said they associated the Proud Boys with hate groups or white nationalism. The Capitol can be seen in the distance from parts of the courthouse, where a second group of Oath Keepers are also currently on trial for seditious conspiracy, which carries up to 20 years behind bars.

Tensions bubbled over at times as jury selection slowed to a crawl and defense lawyers complained that too many potential jurors were biased against the Proud Boys. Defense attorneys challenged jurors who expressed support for causes such as Black Lives Matter, saying that could indicate prejudice against the Proud Boys.

Lawyers and the judge clashed during sometimes chaotic pretrial legal wrangling to the point where two defense attorneys threatened to withdraw from the case. U.S. District Judge Timothy Kelly, a Trump appointee, lashed out after defense lawyers repeatedly interrupted and talked over him on Wednesday, warning that he would find them in contempt if it continued.

Defense lawyers have said there was never any plan to go into the Capitol or stop Congress’ certification of the electoral vote won by Biden. They have accused prosecutors of trying to silence potential defense witnesses — including a Washington police officer in communication with Tarrio in the run-up to the riot — by threatening them with possible charges. Prosecutors have strongly denied those claims.

Tarrio’s lawyers have not said whether he will take the stand in his defense.

Tarrio’s co-defendants are Ethan Nordean of Auburn, Washington, who was a Proud Boys chapter president; Joseph Biggs of Ormond Beach, Florida, a self-described Proud Boys organizer; Zachary Rehl, who president of the Proud Boys chapter in Philadelphia; and Dominic Pezzola, a Proud Boy member from Rochester, New York.

Tarrio, who’s from Miami, wasn’t in Washington on Jan. 6 because he was arrested two days before the riot and charged with vandalizing a Black Lives Matter banner at a historic Black church during a protest in December 2020. He was ordered to leave the capital, but prosecutors say he remained engaged in the extremist group’s planning for Jan. 6.

Prosecutors are expected to tell jurors that as the Proud Boys’ anger over the election grew, they also began to turn against police over Tarrio’s arrest and over the failure to bring charges in the stabbing of another Proud Boy during clashes the month before the riot.

Communications cited in court papers show the Proud Boys discussing storming the Capitol in the days before the riot. On Jan. 3, someone suggested in a group chat that the “main operating theater” be in front of the Capitol. “I didn’t hear this voice note until now, you want to storm the Capitol,” Tarrio said the next day in the same chat.

Tarrio’s lieutenants were part of the first wave of rioters to push onto Capitol grounds and charge past police barricades toward the building, according to prosecutors. Pezzola used a riot shield he stole from a Capitol Police officer to break a window, allowing the first rioters to enter the building, prosecutors allege.

Prosecutors say Tarrio cheered on the actions of the Proud Boys on the ground as he watched from afar.

“Do what must be done. #WeThePeople.” he wrote on social media as the riot unfolded. “Don’t (expletive) leave,” Tarrio wrote in another post.