WASHINGTON - The congressional investigation into the riot at the U.S. Capitol last January is zeroing in on why then-President Donald Trump did nothing for more than three hours to stop his supporters from ransacking the building and clashing with police as lawmakers sought to certify that he had lost the 2020 election, the panel's chairman said Sunday.

Congressman Bennie Thompson of Mississippi told CNN's "State of the Union" show that the nine-member investigative panel wants to know what Trump was doing during "187 minutes of inaction," as he watched the riot unfold on television from a dining room off the Oval Office at the White House.

"We came perilously close to losing our democracy," Thompson contended.

One of the committee's two Republicans, Congresswoman Liz Cheney of Wyoming, a vocal critic of Trump, told ABC's "This Week" show, "He could have told [the rioters] to stand down. He didn't do it."

Thompson said, "The president has been in court trying to prevent us from seeing the record" of his phone calls, other messages and documents as his daughter Ivanka Trump, Republican lawmakers and Trump administration officials urged him to make a statement urging more than 800 of his supporters inside the Capitol to leave the building.

"What he's doing is typical Donald Trump modus operandi," Thompson said. "He sues, goes to court, tries to delay. But we're convinced we'll have access to those 187 minutes."

A U.S. appellate court in Washington has ruled that the investigative committee has a "uniquely vital interest" in seeing any documents related to the riot and its planning, but Trump has appealed to the Supreme Court to overturn the lower court's ruling, saying his White House documents should be shielded from public release.

At a rally near the White House before the January 6, 2021 rioting unfolded, Trump urged supporters to "fight like hell" at the Capitol to keep lawmakers from certifying that Democrat Joe Biden had defeated him in the November 2020 election. More than 725 of the rioters have been arrested and charged with an array of offenses, from minor ones like trespassing to more serious crimes, including attacks on police.

FILE - Pro-Trump protesters storm the U.S. Capitol to contest the certification of the 2020 U.S. presidential election results by the U.S. Congress, at the U.S. Capitol Building in Washington, Jan. 6, 2021.

While ignoring initial entreaties to call off the protesters, Trump eventually released a short video calling for the rioters to leave, but telling them, "We love you; you're very special.'

As he does to this day, Trump mentioned in the video the false conspiracy theory that he actually won the election, saying, 'I know your pain; I know you're hurt. We had an election that was stolen from us. It was a landslide election and everyone knows it. Especially the other side. But you have to go home now. We have to have peace.'

After the Capitol was eventually cleared of protesters, Congress certified Biden's election victory in the early hours of January 7.

Thompson said his panel, which includes seven Democratic lawmakers, Cheney and another vocal Republican critic of Trump, Congressman Adam Kinzinger of Illinois, is looking closely at the planning behind the attack on the Capitol as some Trump Republican stalwarts attempted to keep him in office and thwart Biden's inauguration last January 20.

Thompson said, "We know [Trump] wanted people" to come to Washington, telling them it was "going to be wild."

Of particular interest, Thompson said, were conversations involving the White House and Trump officials at the nearby Willard Hotel in the lead-up to the rally and during the riot at the Capitol.

"It was not a comedy of errors, I can assure you of that," Thompson said. "We'll get to what we believe was the truth.'

"It appeared to be a coordinated effort among a number of people to undermine the election," Thompson said in an interview on ABC, not a spontaneous protest that got out of hand as protesters stormed past barriers into the Capitol, smashed windows and doors and scuffled with police.

He said the panel is seeking to interview two Trump-supporting Republican lawmakers, Congressmen Scott Perry of Pennsylvania and Jim Jordan of Ohio, who played roles in trying to overturn Biden's victory.

"I would hope they'd come in voluntarily" to testify to the committee, Thompson said, but did not rule out subpoenaing them.

He declined to speculate on whether the committee could refer evidence of wrongdoing in the planning of the January 6 demonstration and Trump's inaction during it to the Justice Department for possible prosecution. But he said the panel will not shy away from doing so if it decides such a referral is warranted.

Trump did not attend Biden's inauguration on January 20, 2021 and has continued to contend the election was stolen from him.

Trump has increasingly made political appearances, hinting at a possible 2024 campaign to retake the White House. Trump has announced plans for a Thursday news conference at his Florida retreat along the Atlantic Ocean on the one-year anniversary of the Capitol riot.