Senators Spar Over Voting Rights and the Filibuster

“If the Senate cannot protect the right to vote, which is the cornerstone of our democracy, then the Senate rules must be reformed,” Mr. Schumer said.

The Democrats’ plan, unveiled in a private party meeting on Tuesday night, would still require a partisan vote to change the rules, meaning it cannot succeed at this point given resistance from at least two Democrats.

No Republican currently supports the voting rights measure, which combines two far-reaching bills intended to protect access to the ballot box, leaving Democrats 10 votes short in the evenly divided Senate.

As debate got underway, many Democrats were seated at their mahogany desks on the floor, a show of force they planned to continue throughout the day for what they consider a historic debate. Republicans, by contrast, were mostly absent.

When they did appear, it was to rail against the legislation and Democrats’ portrayal of its opponents as bigots trying to enable voting restrictions aimed at people of color.

“I am not a racist,” said Senator John Thune of South Dakota, the No. 2 Senate Republican.

The impasse has led to intensifying calls to unilaterally change filibuster rules so Democrats can bulldoze over Republicans’ objections. But at least two Democrats, Senators Kyrsten Sinema of Arizona and Joe Manchin III of West Virginia, have made clear they will not do so, even though they support the legislation.

Republicans strongly pushed back on that effort. Senator Mitch McConnell of Kentucky, the minority leader, reiterated his threat that Republicans would use its power to virtually shut down the Senate should Democrats successfully execute what is known as the “nuclear option” and gut the filibuster.

“The Senate in nuclear winter would not be a hospitable place,” he warned.