Biden spoke via phone with the "Tennessee Three" and "thanked them for their leadership in seeking to ban assault weapons," a White House statement said.

Biden invited the three to the White House "in the near future," it added.

The Republican-led Tennessee House of Representatives expelled two Black lawmakers on Thursday after they disrupted an assembly session to demand stricter gun controls in the wake of a deadly mass shooting at an elementary school. A third white legislator who joined their protest was not removed.

Accusations of racism have reverberated around the case, and sparked anger among Democrats well beyond Tennessee.

Harris, the nation's first Black vice president, arrived in Nashville in a clear message of solidarity with the three officials. She attended a rally at Fisk University, a historically black institution, and met with the three Democrats targeted over the gun protests.

On March 30, just days after a shooting rampage at a Christian school killed six people, legislators Justin Jones, Justin Pearson and Gloria Johnson joined hundreds of protesters on the state House floor to challenge lawmakers to favor stricter gun control.

Jones and Pearson used a bullhorn to shout "Gun control now" and "Power to the people" while rallying protesters in the galleries.

The extremely rare move to expel the lawmakers caused an uproar, with Biden calling it "shocking, undemocratic, and without precedent," and reiterated calls for America to overcome its divisions to tackle the scourge of gun violence.

Their protest followed the shooting death of three young students and three staff at a private Christian elementary school in the state capital on March 27.

"Silencing the voices of two Black members for peacefully protesting gun violence is not only racist but also a radical shift away from the democratic rules & traditions our nation was founded upon," tweeted Yvette Clarke, a Black congresswoman from New York.

- 'Jim Crow-era' -

The legislature voted mostly along party lines on Thursday to expel Jones and Pearson for breaching floor rules. A vote to expel Johnson failed by one vote, with half a dozen Republicans joining Democrats to vote against her expulsion.

Jesse Chism, a Democratic state legislator, compared the vote to the era of racial segregation.

"It looked like a Jim Crow-era trial," he said.

Johnson voiced a similar view, telling CNN: "Well, I think it's pretty clear. I'm a 60-year-old white woman and they are two young Black men."

Jones, 27, and Pearson, 28, delivered impassioned pleas against their exclusion and a photo of them raising their fists went viral.

Speaking to MSNBC, Jones called the expulsion "a dangerous precedent for the nation" and a "direct assault on democracy," urging the Justice Department to look into the legality of the move.

"If you didn't tell me this was happening to me, I would think it was 1963 instead of 2023," he went on.

"Because what we're seeing is a predominantly white supermajority, undoing democracy, forcing their will on my district which is a predominantly Black and brown district, one of the most diverse in Tennessee."