Joe Biden planned to use a speech in Georgia on Tuesday to make his most detailed case yet for passing sweeping voting rights legislation and to throw his support behind changing the Senate’s filibuster rules to allow such action, calling it a moment to choose “democracy over autocracy”.

But some civil rights activists, proclaiming themselves more interested in action than speeches, said they planned to stay away.

The speech comes at a pivotal moment for Democrats.

Chuck Schumer, the Senate majority leader, has said he will hold a vote no later than 17 January, a federal holiday to celebrate civil rights leader Martin Luther King, on voting rights legislation.

If Republicans as expected use the filibuster, which requires 60 votes to advance legislation, to block the measure, Schumer has said he will hold a vote on changing filibuster rules.

It is not clear that two key Democratic holdouts, Joe Manchin of West Virginia and Kyrsten Sinema of Arizona, are on board with the changes.

On Tuesday, Biden was expected to evoke memories of the US Capitol riot a year ago in more forcefully aligning himself with the effort.

Biden planned to tell his audience: “The next few days, when these bills come to a vote, will mark a turning point in this nation.

“Will we choose democracy over autocracy, light over shadow, justice over injustice? I know where I stand. I will not yield. I will not flinch,” he will say, according to prepared remarks.

“I will defend your right to vote and our democracy against all enemies, foreign and domestic. And so the question is: where will the institution of United States Senate stand?”

A White House official said Biden would voice support for changing filibuster rules to ensure the right to vote was defended – a strategy Democrats have been looking to the president to embrace.

Some voting rights advocates planned to boycott the speech and instead spend the day working. The Democratic gubernatorial candidate Stacey Abrams, known for her voting rights work, was also due to skip the event. Aides said Abrams had a conflict but did not elaborate.

So far, Democrats have been unable to agree potential changes to filibuster rules to allow action on voting rights, despite months of negotiations.

Voting rights advocates are increasingly anxious about elections in 2022 and beyond, following enactment of Republican-pushed laws that make it harder to vote, inspired by Donald Trump’s loss in 2020 and his push to overturn it, despite no evidence of widespread fraud.

The Democratic senator Raphael Warnock, senior pastor of a church Biden will visit and who made history as the first Black senator elected in Georgia, said: “Anything that can happen that will continue to shine a bright light on the urgency of this issue is important.”

Warnock planned to travel with Biden to Georgia on Tuesday. He said he believed Biden understood that “democracy itself is imperilled by this all-out assault that we’ve been witnessing by state legislatures all across the country, and this is a moral moment. Everybody must show up.”

The White House press secretary, Jen Psaki, rejected some activists’ complaints that Biden had not been a strong enough advocate.

“I think we would dispute the notion that the president hasn’t been active or vocal. He’s given a range of speeches, he’s advocated for voting rights to pass,” she said

Biden gave a speech in Philadelphia this summer on the need to protect voting rights, but it wasn’t until October that he endorsed getting rid of the filibuster for voting rights laws. Activists have expressed deep frustration that the White House wasn’t moving aggressively enough.

Laws have already passed in at least 19 states that make it more difficult to vote. Voting rights groups view the changes as a subtler form of the ballot restrictions such as literacy tests and poll taxes once used to disenfranchise Black voters.

Republicans who have fallen in line behind Trump are separately promoting efforts to influence future elections by installing sympathetic leaders in local election posts and backing for elective office some of those who participated in the riot at the US Capitol a year ago.

“Joe Biden and Democrats’ election takeover attempts are blatant power-grabs designed to rig the game,” Ronna McDaniel, the chair of the Republican National Committee, said in a statement on Tuesday.

“Democrats want to destroy the integrity of our elections by eliminating photo ID requirements, allowing non-citizens to vote, using taxpayer dollars to fund career politicians, and silencing voters.”

Georgia, one of the key battleground states in 2020, is at the centre of it all. After its vote was certified, Trump told a top state official he wanted the official to “find” enough votes to overturn his loss. The state nonetheless went to Biden, and both of its Senate seats to Democrats.

Last year, the Republican governor signed a sweeping rewrite of election rules that, among other things, gives the state election board new powers to intervene in county election offices and remove and replace officials. That has led to concerns that the Republican-controlled state board could exert more influence over elections, including the certification of county results.

Georgia voting activists said they worked tirelessly to give Democrats the Senate and White House, and it was time for Washington to step up.

Congressional Democrats have written voting legislation that would usher in the biggest overhaul in a generation by striking down hurdles to voting enacted in the name of election security, reducing the influence of big money in politics and limiting partisan influence over the drawing of congressional districts.

The package would create national election standards to trump state-level GOP laws. It would also restore the ability of the justice department to police election laws in states with recent evidence of voting discrimination.

But to pass the legislation – which Republicans have outright rejected – the Democrats say they must change the Senate rules that allow a minority of 41 senators to block a bill.