Former President Donald Trump did "nothing" to stop the riot at the Capitol as it was unfolding on Jan. 6, 2021, and new witnesses will fill in the gaps in Trump's activities that day when the House select committee investigating the attack holds its next hearing, members of the bipartisan panel said Sunday.

Rep. Adam Kinzinger, R-Ill., who is scheduled to lead the prime-time hearing on Thursday, said the session "is going to open people's eyes in a big way" as they examine Trump's actions in detail over the hours the Capitol was overrun by a mob seeking to stop the certification of Joe Biden's electoral college win.

"We have filled in the blanks," Kinzinger said on CBS's Face the Nation on Sunday. Trump "didn't do very much but gleefully watch television during this time frame."

Kinzinger, one of two GOP members of the bipartisan panel who has come under regular attacks from Trump for his role on the committee, implored his fellow Republicans to watch the next hearing with an open mind and ask themselves: "Is this the kind of strong leader you really think you deserve?"

Late Friday, the committee took the unusual step of subpoenaing the Secret Service after reports the agency erased text messages from Jan. 5 and Jan. 6, 2021, after the Department of Homeland Security's Office of Inspector General had requested them. Committee members said they expect to receive the text messages by Tuesday.

"An agency that was such a key part of a critical event in our history, one would assume they had done everything possible to preserve those records," Rep. Elaine Luria, D-Va., said on CNN's "State of the Union." "As far as digital records and text messages, not being an I.T. expert, but I do understand there's a lot of things that can be done, a lot of forensic analysis and recouping of data."

Previous hearings have focused on Trump's efforts to pressure the Justice Department, state officials and his own vice president to overturn the results of the 2020 election; Trump's own rampage as he was prevented from traveling to the Capitol with his supporters that day; and the ties between the Trump White House and violent extremist groups that were part of the attack. But so far, the committee has publicized little about what Trump was doing during the Capitol riot, after he had returned to the White House.

The hearing on Thursday will be the final one in the first series, but committee members said there could be more hearings later in the year.

"If we get information that the American people need to know, we may end up bringing more hearings at that time, too," Kinzinger said.

Committee members said Sunday that Trump didn't intervene in the 187 minutes between when he left his "Stop the Steal" rally on the Ellipse that day to when he at last tweeted out a video at 4:17 p.m. telling his supporters to leave the Capitol.

"It's pretty simple: He was doing nothing to actually stop the riot," Luria said.

"We will go through pretty much minute by minute during that time frame, from the time he left the stage at the Ellipse, came back to the White House, and really sat in the White House, in the dining room, with his advisers urging him continuously to take action, to take more action," Luria added.

Luria also referenced the now-infamous tweet sent at 2:24 p.m. that day accusing Vice President Mike Pence of not having "the courage to do what should have been done," further inflaming the situation.

Asked if Trump's inaction would constitute a crime, Luria said that Trump should have understood what action looked like in a time of crisis as the nation's commander in chief.

"He is the only person in the Constitution whose duty is explicitly laid out to ensure that the laws are faithfully executed," said Luria, a military veteran. "I look at it as a dereliction of duty."

Both Luria and Kinzinger said the committee is continuing to seek and receive new information every day about the Jan. 6 attack.

Rep. Zoe Lofgren, D-Calif., said on ABC's "This Week" that the committee plans to publish a final report later this year.

"This investigation is very much ongoing. The fact that series of hearings is going to be concluded this Thursday doesn't mean that our investigation is over," Lofgren said.

"Frankly, if the president's supporters had not engaged in frivolous litigation for months on end, we would be farther along than we are," Lofgren said.

Kinzinger also once again defended Cassidy Hutchinson, a former aide to Trump chief of staff Mark Meadows, who testified last month that she was told Trump lunged at his Secret Service detail in anger while inside the presidential limousine because they wouldn't drive him to the Capitol.

Anonymous sources have since disputed her testimony, but Kinzinger said the committee was still working on speaking to those who were in the presidential limo at the time and that any statements would have to be made under oath.

"We have every reason to believe that what Cassidy Hutchinson said, at least from what she said she heard, because she wasn't in the limo - never said she was," Kinzinger said. "She was told this. We fully believe that she is a credible witness and her allegations are quite explosive."

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The Washington Post's Joanna Slater and Ariana Eunjung Cha contributed to this report.