The hearing began shortly after 10 a.m. with the defense calling Mark Meadows to the stand.

The defense went over Meadows' duties as chief of staff and assistant to former President Donald Trump.

On the stand, Meadows said it was his role to "oversee all the federal operations, not just in the West Wing, but beyond that."

Meadows also said the job was difficult in light of the pandemic, calling it "challenging times."

"There was a political component to everything that we did," Meadows said in describing the intersection between policy and politics inside the Trump White House in the chaotic closing days of the administration.

Meadows, wearing a royal blue suit, white shirt and pale blue tie in court, said he attended meetings as a principle and sometimes as an observer.

Meadows said he would "certainly meet with state officials" as part of his job.

At least one attorney for Trump, Jennifer Little, was spotted in the overflow room listening to the proceedings.

-ABC News' Nadine El-Bawab and Aaron Katersky

Fulton County, Georgia, Superior Court Judge Scott McAfee has scheduled the plea hearings and arraignments for all 19 defendants alleged to have conspired to overturn the 2020 election for Wednesday, Sept. 6.

The arraignments are staggered over 15-minute intervals, beginning with former President Donald Trump at 9:30 a.m. and concluding with Misty Hampton at 3 p.m.

Former chief of staff Mark Meadows' appearance is scheduled for 10:30 a.m.

-ABC News' Peter Charalambous

Former White House chief of staff Mark Meadows arrived at federal court in Atlanta just after 9 a.m. ET for a hearing on his motion to have his trial moved from state to federal court.

Meadows walked in with his lawyers and did not respond to any shouted questions.

-ABC News' Lalee Ibssa

As Meadows heads to court Monday, multiple sources close to some of the 18 other Georgia defendants -- which include Trump and former New York City Mayor Rudy Giuliani -- have told ABC News that the legal teams for many of the defendants will be keeping a "close eye" on the proceedings, with some even sending people to watch in person.

Many involved in the case are uncertain what the ramifications would be if Meadows' case is moved to federal court, the sources said, and whether it would bring along all 19 defendants or leave their cases in state court.

"It is completely untested," one attorney for a defendant in the case told ABC News.

Mark Meadows testified that the Hatch Act does apply to the White House chief of staff, but he said “there are some differences of opinion on how it should apply.”

Meadows insisted that when it comes to his interactions with people connected to Donald Trump's campaign, including Georgia Secretary of State Brad Raffensperger, he said, "I didn't [see ] that as a violation of the Hatch Act."

The Hatch Act limits the political participation and speech of federal employees.

-ABC News' Mike Levine