Who is Matthew Pottinger? The former Trump National Security aide expected to testify during January 6 hearing

• Ex-Trump national security advisor Matthew Pottinger is slated to testify at a January 6 committee hearing.
• Pottinger was among a number of White House officials who resigned following the Capitol riot.

Former national security aide Matthew Pottinger, who was the highest ranking Trump White House official to resign in the wake of the Capitol riot, is expected to testify at Thursday's primetime January 6 hearing, according to multiple reports.

Pottinger was appointed as a deputy adviser to former President Donald Trump in September 2019. He resigned the afternoon of January 6, 2021, amid a wave of resignations following the violence at the Capitol.

GOP Rep. Liz Cheney of Wyoming, who serves as the vice chairwoman of the House panel investigating the Capitol riot, described Pottinger as a "former Marine intelligence officer who served in the White House for four years, including as deputy national security adviser, was in the vicinity of the Oval Office at various points throughout the day."

The former Trump-era official is slated to appear before the House January 6 committee along with former deputy press secretary Sarah Matthews — both of whom spent most of January 6, 2021, inside the White House. Both are expected to paint a picture of what transpired inside the Oval Office as a mob of pro-Trump supporters stormed the US Capitol.

In an interview clip played during a previous January 6 public hearing, Pottinger recalled the moment he decided to leave the Trump White House, prompted by the former president's response to the violence ensuing at the Capitol.

"One of my staff brought me a printout of a tweet by the President, and the tweet said something to the effect that Mike Pence, the vice president, didn't have the courage to do what he — what should have been done," Pottinger said in the clip. "I read that tweet and made a decision at that moment to resign. That's where I knew that I was leaving that day once I read that tweet."

Pottinger had initially intended to step down from his role on the day of the 2020 election — regardless of the outcome — but stayed at the request of then-National Security Adviser Robert O'Brien, Bloomberg reported.

A person familiar with Pottinger's videotaped testimony told The New York Times that, while Pottinger said he did not speak to Trump on January 6, 2021, he did visit the Oval Office to notify then-White House Chief of Staff Mark Meadows that the National Guard had still not arrived to the Capitol.

Meadows, seemingly frustrated, replied saying he had made several calls to the Pentagon to deploy the National Guard, per The Times report.

Insider could not immediately reach Pottinger for comment.