WASHINGTON — 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, and 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 designed to invigorate a Democrat-led effort to pass new voting rights protections in the 50-50 Senate in coming days. But it is also a gamble for Mr. Biden, who has exhausted his political capital on other efforts, including a bipartisan infrastructure deal and a stalled social spending plan.

Now, as he turns to voting rights, Mr. Biden faces huge obstacles in getting the legislation past Republican opposition. 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 presiding to break a tie.

Democratic Senators Joe Manchin III of West Virginia and Kyrsten Sinema of Arizona have expressed strong public opposition to changing filibuster rules.

Many Democrats say such a carve-out would apply only to issues grounded in constitutional rights such as voting, but Republicans and others say it would inevitably be extended to other legislation, diminishing the overall power of the filibuster.

Aware of mounting frustrations among his allies who say he has not done enough as restrictive voting measures pass through Republican-led statehouses around the country, Mr. Biden’s advisers have promised that he will be forceful about his support for two voting rights bills that could beat back those efforts.

One bill introduced by Democrats, the Freedom to Vote Act, would, among other provisions, take the teeth out of state-led efforts to restrict mail-in or absentee voting, make Election Day a holiday, and stop state legislators from redrawing districts in a way that advocates say denies representation to minority voters. Another, the John Lewis Voting Rights Advancement Act, would restore crucial anti-discrimination components of the Voting Rights Act that were stripped away by the Supreme Court in 2013.

Jen Psaki, the White House press secretary, acknowledged that expectations around the speech were high: “He wouldn’t be going to Georgia tomorrow if he wasn’t ready and prepared to elevate this issue and continue to fight for it,” Ms. Psaki told reporters on Monday.

But the president’s advisers have been far less specific about what solutions he might offer, and a bipartisan path forward is all but impossible. Mr. Biden, who spent 36 years in the Senate and sees himself as a consensus builder, has faced resistance from Republicans on voting rights legislation.

Last week, Chuck Schumer, Democrat of New York and the majority leader, said Republicans could have until Monday, Martin Luther King Jr. Day, to drop their opposition to debate and votes on the issue, or face the prospect of overhauling Senate filibuster rules.

Senator Mitch McConnell, Republican of Kentucky, promised a scorched-earth response should Democrats go that route: “Since Sen. Schumer is hell-bent on trying to break the Senate, Republicans will show how this reckless action would have immediate consequences,” Mr. McConnell said in a statement on Monday.

Republicans have argued that Democrats are using the voting rights legislation to try to gain partisan advantage by seeking to impose their preferred rules on states that have long regulated their own elections. But activists say that critique ignores glaring examples of voter suppression. Voting rights groups in Georgia have already filed a federal lawsuit that accuses legislators of redrawing a congressional district to benefit Republican candidates and deny representation to Black voters.

On Tuesday, Mr. Biden will lean on the power of symbolism when he travels to Georgia. Mr. Biden and Ms. Harris will visit the crypt of the Rev. Dr. Martin Luther King Jr. and his wife, Coretta Scott King. They will visit the historic Ebenezer Baptist Church, where both Dr. King and Mr. Lewis, the Georgia congressman and civil rights icon for whom the legislation is named, were eulogized. Sen. Raphael Warnock, the state's first Black senator and a Democrat who is seeking a full term this year after a runoff victory, is a senior pastor there.

In the afternoon, Mr. Biden and Ms. Harris will speak at theAtlanta University Center Consortium, a consortium of four historically Black colleges and universities. On Monday evening, the vice president’s office said that Ms. Harris, whom Mr. Biden had asked to lead on the issue, “will reaffirm that securing the right to vote is essential to safeguarding and strengthening our democracy” in her remarks.

Georgia, a state Mr. Biden won by just 11,779 votes, has also seen some of the most sweeping attempts by Republicans to assert partisan power in elections, particularly through restricting mail-in, absentee or early voting. Critics say similar laws have mushroomed around the country in response to false claims by former President Donald J. Trump and his supporters that the 2020 election was rigged. Last week, marking the anniversary of the attack on the United States Capitol, Mr. Biden denounced those theories: “You can’t be patriotic when you embrace and enable lies.”

Some prominent activists are offering tempered support ahead of the president’s speech, angered by what they feel is a lack of attention as state-level restrictions go into effect.

Rep. Terri A. Sewell, Democrat of Alabama, who introduced the bill named for Mr. Lewis in August, said that she was “pretty clear” what her expectations were before she agreed to travel aboard Air Force One to Atlanta with Mr. Biden and Ms. Harris. She said she had been assured that the president would not only talk about the need for voting rights, but outline a plan for getting it done that would embrace a change of Senate rules.

“It was Georgia voters that gave him the presidency and gave us the slim majority that we have in the Senate,” Ms. Sewell said. “I know that he knows that we may have to walk this alone.”

Others are declining to attend. Stacey Abrams, the voting rights advocate and Democratic candidate for governor in Georgia, will not be able to attend the speech because of a conflict, an aide to Ms. Abrams said. The person declined to elaborate on the conflict.

One prominent family will attend. Martin Luther King III, the oldest living son of the civil rights leader, and his wife, Arndrea Waters King, will meet with Mr. Biden in Atlanta. Mr. King said that he would meet with the president and tell him that his visit to Georgia can’t be just a formality.

“We’ve seen what’s possible when President Biden uses the full weight of his office to deliver for bridges,” Mr. King said in a statement. “And now we need to see him do the same for voting rights.”

Nick Corasaniti contributed reporting from New York.