By Patricia Zengerle

WASHINGTON (Reuters) - A former campaign manager for ex-President Donald Trump and former officials from Atlanta and Philadelphia will testify on Monday to the U.S. congressional committee investigating the January 6, 2021, attack on the Capitol, the committee said on Sunday.

The House Select Committee will hold its second public hearing this month on Monday starting at 10 AM ET, after a blockbuster session on Thursday night where the panel presented testimony showing that close Trump allies - even his daughter Ivanka - rejected his false claims of voting fraud.

The hearing on Monday, the second of six this month, will focus on the former Republican president's contention that his defeat by Democrat Joe Biden in the November 2020 election was due to unfounded allegations of election fraud, the so-called "Big Lie."

The first panel of witnesses at the hearing will include William Stepien, who served as campaign manager for Trump's 2020 campaign, after serving as Trump's White House director of political affairs from 2017 to 2018.

Also testifying at the first panel will be Chris Stirewalt, a former political editor of Fox News.

The second panel will include conservative Republican election attorney Ben Ginsberg; BJay Pak, who resigned as a U.S. attorney in Atlanta as Trump and his allies sought to overturn results of the election in Georgia; and Al Schmidt, who was the only Republican on the city of Philadelphia's elections board and became a target of attacks by Trump after he defended the integrity of the 2020 presidential vote.

Georgia and Pennsylvania were among states that backed Trump in the 2016 election, but fell into Biden's column in 2020. They have been a focus of the unfounded assertions of election fraud.

(Reporting by Patricia Zengerle, editing by Chris Reese)