President Biden will endorse changing Senate rules to pass new voting rights protections during a speech in Atlanta on Tuesday, the most significant step he will have taken to pressure lawmakers to act on an issue he has called the biggest test of America’s democracy since the Civil War.

Mr. Biden will not go so far as to call for full-scale elimination of the filibuster, a Senate tradition that allows the minority party to kill legislation that fails to garner 60 votes, according to a senior administration official who previewed the speech. But Mr. Biden will say he supports a filibuster “carve-out” in the case of voting rights, the official said.

Citing “repeated obstruction” by Republicans, Mr. Biden will endorse changing the Senate rules, the official said. The president will contend that the filibuster has protected “extreme attacks on the most basic constitutional right.”

“The next few days, when these bills come to a vote, will mark a turning point in this nation,” Mr. Biden will say on Tuesday, according to a preview of his remarks provided by the White House. “Will we choose democracy over autocracy, light over shadow, justice over injustice? I know where I stand.”

Mr. Biden’s visit to Georgia is intended to invigorate a Democratic-led effort to pass new voting rights protections in the 50-50 Senate in the coming days, although chances are slim that he will be able to rally the necessary votes. And even with his new call for a filibuster carve-out, changing the Senate rules would require the support of all 50 Democrats and the vote of Vice President Kamala Harris to break a tie. Senators Joe Manchin III of West Virginia and Kyrsten Sinema of Arizona, both Democrats, have expressed strong public opposition to changing filibuster rules.