In the final hours of debate, Democrats pressed the need for action — including a rare rules change that threatened to upend decades of Senate procedure — in lofty terms couched in the preservation of democracy, while Republicans angrily countered with accusations that the maneuver amounted to nothing more than a partisan power play.

“Shall we see American democracy backslide in our time, grow feeble in the jaws of its adversaries, and ultimately succumb to the cancer of voter suppression?” Schumer said Wednesday. “The answer, in a large sense, could depend on how we move forward this evening.”

Sen. Raphael G. Warnock (D-Ga.), who faces reelection this year in one of the states subject to new GOP voting laws, compared the vote to late activist and congressman John Lewis’s bloody trip across a Selma, Ala., bridge during a 1965 voting rights march.

“We’re talking about a procedural bridge,” he said. “I’m still praying that we will cross that bridge. But if not tonight, we will come back again and again and again.”