Sinema was one of two Democratic senators who joined with Republicans to vote against lowering the Senate's 60-vote threshold to 50 so that the Senate could pass voting rights bill without bipartisan support.

The censure is mostly a symbolic move, but it does highlight criticism that Sinema has faced from members of her own party, with polling indicating that Sinema is facing a rising amount of backlash from Democratic voters.

Raquel Teran, the state party's chair, said in a Saturday statement they supported Sinema's votes to pass legislation to provide more coronavirus relief and to improve the nation's infrastructure.

"However, we are also here to advocate for our constituents and the ramifications of failing to pass federal legislation that protects their right to vote are too large and far-reaching," Teran said.

"While we take no pleasure in this announcement, the ADP Executive Board has decided to formally censure Senator Sinema as a result of her failure to do whatever it takes to ensure the health of our democracy," Teran added.

The failure to pass the legislation was a major blow to President Joe Biden's legislative agenda and for voting rights groups, which had been fighting a slate of laws passed in Republican-controlled states that election experts have said were designed to suppress voting, especially among Black, Hispanic and poor voters.

Experts and voting rights advocates say the states have passed the legislation largely to back former President Donald Trump's false claims that the 2020 election was marred by rampant fraud.

In Sinema's home state of Arizona, state Senate Republicans contracted a private company called Cyber Ninjas to perform a so-called "audit" of the 2020 election. Election officials discredited the probe, with Arizona's Secretary of State issuing a report saying the election was secure and accurate and calling the review "secretive and disorganized."

The company has since shut down after a judge ordered it to pay $50,0000 a day in fines, according to media reports.

Sinema co-sponsored the Senate version of election overhaul legislation, but has publicly stated repeatedly she opposed changing filibuster rules.

Sinema's office shrugged off the censure in a statement.

"During three terms in the U.S. House, and now in the Senate, Kyrsten has always promised Arizonans she would be an independent voice for the state - not for either political party. She's delivered for Arizonans and has always been honest about where she stands," a spokesperson said.

(Reporting by Makini Brice; Editing by Aurora Ellis)