Omar lashed out at her upper chamber counterparts, who have stood against progressive appeals to nix the filibuster, blaming them for being the death knell of democracy.
"The filibuster—and the Democratic Senators who continue to uphold it—are killing our democracy," she tweeted on Wednesday.
The filibuster is a Senate procedure in which a senator or group of senators debate a bill for so long that the measure does not get voted on. The system gives the minority party in the Senate a robust oppositional voice, with a Senate filibuster being broken by a cloture vote with 60 votes in favor.
Wednesday's filibuster is the third time this year that Senate Republicans have obstructed the Democrats' voting overhaul agenda.
Progressives have been strong in their calls for the abolition of the filibuster. However, moderate Democrat Sens. Joe Manchin of West Virginia and Kyrsten Sinema of Arizona have protested the removal of the Senate procedure.
The Senate voted 49-51 on whether to take up the "Freedom to Vote Act," falling far short of the 60 votes needed to defeat a GOP filibuster. Senate Majority Leader Chuck Schumer, D-NY, switched his vote to a "nay" in a procedural move that will allow him to submit the legislation for a re-vote.
President Biden slammed Republicans for blocking consideration of the voting rights legislation in a scathing statement, arguing the right to vote is "under unrelenting assault by proponents of the Big Lie and Republican Governors, Secretaries of State, Attorneys-General, and state legislatures across the nation."
Senate Minority Leader Mitch McConnell, R-Ky., had promised that Republicans would oppose the measure.
"It is my hope and anticipation that none of us will vote for this latest iteration of Democratic efforts to take over how every American vote all over the country," he declared Tuesday.
Sen. Lisa Murkowski of Alaska, the Republican who has been most willing to engage with Democrats over voting rights, explained her vote to block the bill earlier, stating she was more interested in the House-passed John Lewis Voting Rights Advancement Act.
The Freedom to Vote Act would enable automatic and same-day voter registration and no-excuse mail voting. It would give states flexibility in performing some provisions, like early voting and making Election Day a holiday. It further would seek to shield federal election records and insulate nonpartisan state and local election officials from undue interference.