The powerful political action committee said the Arizona senator could find herself “standing alone” in 2024 if she refuses to change Senate rules to force through voting rights legislation.

WASHINGTON — One of the largest contributors to Senator Kyrsten Sinema’s political rise announced on Tuesday that it would cut off its financial support if the senator continues to refuse to change the Senate’s filibuster rules to allow for passage of far-reaching voting rights legislation.

Emily’s List, the largest funder of female Democratic candidates who support abortion rights, made the extraordinary announcement as the Senate barreled toward votes this week on a bill to reverse restrictions on voting passed by a number of Republican-led state legislatures.

If, as expected, Republicans block the bill with a filibuster, Democratic leaders plan to try to change the Senate’s rules to overcome the minority party’s opposition.

Sinema, Democrat of Arizona, has said she will not vote to change the rules, making her — along with another holdout from her party, Senator Joe Manchin III of West Virginia — a target of liberal activists’ ire.

“Understanding that access to the ballot box and confidence in election results are critical to our work and our country, we have joined with many others to impress upon Senator Sinema the importance of the pending voting rights legislation in the Senate,” Laphonza Butler, the president of Emily’s List, said in a statement.

She added, “Right now, Senator Sinema’s decision to reject the voices of allies, partners and constituents who believe the importance of voting rights outweighs that of an arcane process means she will find herself standing alone in the next election.”.

Sinema’s biggest donor in her run for the Senate in 2018, and potential primary challengers for her next run in 2024, such as Representative Ruben Gallego of Arizona, have begun making some noise.

Why are voting rights an issue now?

President Biden endorsed changing the Senate’s filibuster rules to pass the legislation.

Sinema said during a Senate floor speech last week that she supported the voting rights legislation, which would establish a national baseline for early voting, absentee ballots and ballot drop boxes; codify voter identification rules; promote donor transparency; and establish strict rules against the replacement of nonpartisan election officials without cause, among other provisions.

Sinema said she would not support a single party unilaterally dismantling the filibuster, which requires the votes of 60 senators to cut off debate on most legislation.