Raffensperger, along with his deputy Gabe Sterling and Arizona's state House Speaker Rusty Bowers, are scheduled to be the key witnesses when the House committee investigating the January 6, 2021, insurrection resumes on Tuesday.

The focus will be on how the then president and his allies vigorously pressured officials in key battleground states with schemes to reject ballots or entire state tallies to upend the results of the 2020 presidential election.

Additionally, the panel will underscore how Trump knew his unrelenting pressure campaign could potentially cause violence against state and local officials and their families but pursued it anyway.

"We will show courageous state officials who stood up and said they wouldn't go along with this plan to either call legislatures back into session or decertify the results for Joe Biden," California's Adam Schiff, one of the Democratic members of the committee, told CNN on Sunday.

The public hearing, the fourth by the panel this month, is the latest effort to delve into Trump's unprecedented attempt to remain in power, a sprawling scheme that the chairman of the January 6 committee has likened to an "attempted coup".

The committee will review how Trump leaned on Raffensperger to invalidate ballots that voters had cast for Biden, and tapped state legislators in Arizona, Michigan, Pennsylvania and other disputed states to reject the election results from their own voters.

While the committee cannot charge Trump with any crimes, the Justice Department is watching the panel's work closely.

Trump's actions in Georgia are also the subject of a grand jury investigation, with district attorney expected to announce findings this year.

Raffensperger, Georgia's top election official, rebuffed Trump's demand he "find" enough votes to overturn Biden's win in the state - a request caught on tape during a phone call days before the January 6 attack.

During the call, Trump repeatedly cited disproven claims of fraud and raised the prospect of a "criminal offence" if Georgia officials did not change the vote count.

The state had counted its votes three times before certifying Biden's win by a margin of 11,779.

Sterling, Raffensperger's chief operating officer, became a notable figure in Georgia's long post-election counting, and recounting, of the presidential ballots, with his regular updates often broadcast live to a divided nation.

At one point, the mild-spoken Republican implored Americans to tone down the heated rhetoric.

"Death threats, physical threats, intimidation - it's too much, it's not right," said Sterling, a Republican.

The select committee also plans to untangle the elaborate "fake electors" scheme aimed at halting Biden's election win.

The plan saw fake electors in seven battleground states - Arizona, Georgia, Michigan, Pennsylvania, Wisconsin, Nevada and New Mexico - sign certificates falsely stating Trump, not Biden, had won their states.

Conservative law professor John Eastman, a lawyer for Trump, pushed the fake electors in the weeks after the election. Trump and Eastman convened hundreds of electors on a call on January 2, 2021, encouraging them to send alternative electors from states where Trump's team was claiming fraud.

The fake electoral certificates were produced and mailed to the National Archives and Congress. But the effort failed as Vice President Mike Pence refused Trump's repeated demands that he halt the certification of Biden's win on January 6, 2021 - a power he did not possess in his purely ceremonial role.

The committee says it will also show on Tuesday it has gathered enough evidence through its more than 1000 interviews and tens of thousands of documents to connect the varying efforts to overturn the election directly to Trump.

"We will show during a hearing what the president's role was in trying to get states to name alternate slates of electors, how that scheme depended initially on hopes that the legislatures would reconvene and bless it," Schiff said.

Australian Associated Press