Progressive Independent Bernie Sanders Attributes Kyrsten Sinema's Party Switch to 'Political Aspirations'

Alexander Tamargo/Getty; Kent Nishimura / Los Angeles Times via Getty Bernie Sanders (left), Kyrsten Sinema

In the wake of Sen. Kyrsten Sinema's announcement that she is formally leaving the Democratic Party to become an independent, one of the lawmaker's colleagues says the move appears to be motivated by "political aspirations."

"She has her reasons. I happen to suspect that it's probably a lot to do with politics back in Arizona," Vermont Sen. Bernie Sanders — another independent who caucuses with Democrats — told CNN's Dana Bash in a weekend appearance on State of the Union. "I think the Democrats are not all that enthusiastic about somebody who helps sabotage some of the most important legislation that protects the interests of working families and voting rights and so forth."

Sinema, who has positioned herself as one of Senate's biggest disruptors since being elected in 2018, announced last week she would become an independent, saying her decision was one one made with her constituents in mind.

RELATED: Arizona Sen. Kyrsten Sinema Leaves Democratic Party to Become Independent: 'Right for the Country'

In an op-ed written for The Arizona Republic last week, Sinema argued: "There's a disconnect between what everyday Americans want and deserve from our politics, and what political parties are offering."

Sanders isn't convinced, telling CNN: "I think it really has to do with her political aspirations for the future in Arizona."

With her switch, Sinema will now become one of only three independent U.S. senators, joining Sanders and Maine's Angus King, both of whom also caucus with the left and contribute to the Democratic Party's majority.

But some worry that Sinema will be less of a Democratic ally than Sanders and King, who routinely vote blue, and could feel empowered with her newly unaffiliated status to side with Republicans more often.

RELATED: Sen. Kyrsten Sinema Confronted on Video by Activists amid Key Role in Spending Bill Vote

Neither Sanders nor the Democrat-led Biden administration, however, seem worried. Speaking to CNN, Sanders said, "For us, I think, nothing much has changed in terms of the functioning of the U.S. Senate."

That sentiment was echoed by the White House, which was informed of Sinema's intent to leave the president's party last Thursday afternoon, NBC News reports.

An administration official told the network's White House correspondent that they don't believe her decision "changes much except her reelection path." (If she runs for reelection in 2024, she will no longer have to fear losing a Democratic primary, but will have a more difficult time competing with the funding going to major party candidates.)

While Sinema's move is unlikely to shift the power balance in the Senate, where Democrats now hold a majority, it could have an impact on her career in Arizona. Democratic Rep. Ruben Gallego is widely expected to be mulling a run for Sinema's seat.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer.

Gallego slammed Sinema for her party switch in a statement last Friday, saying Arizonans "want leaders who put the people of Arizona first. We need Senators who will put Arizonans ahead of big drug companies and Wall Street bankers."

His statement continued: "Whether in the Marine Corps or in Congress, I have never backed down from fighting for Arizonans. And at a time when our nation needs leadership most, Arizona deserves a voice that won't back down in the face of struggle. Unfortunately Senator Sinema is once again putting her own interests ahead of getting things done for Arizonans."