Washington (AFP) - Arizona Senator Kyrsten Sinema announced Friday that she was leaving the Democratic Party to become an independent in a surprise move just days after President Joe Biden's Democrats increased their slim majority in the chamber.
Sinema's decision is not expected to significantly shift the balance of power in the Senate but it could increase her influence and that of another centrist Democratic senator, Joe Manchin of West Virginia.
"Like a lot of Arizonans, I have never fit perfectly in either national party," the 46-year-old Sinema said in an opinion piece published in the Arizona Republic.
"That's why I have joined the growing numbers of Arizonans who reject party politics by declaring my independence from the broken partisan system in Washington," she said.
Democrats secured a 51-49 majority in the Senate with Raphael Warnock's win this week in the Georgia runoff election and they will retain their hold on the chamber even with Sinema's departure.
Democrats welcomed Warnock's victory in part because it curbed the power of Manchin, who has blocked several of Biden's major policy initiatives, and Sinema, who has also been a thorn in the side of the president at times.
There are two other independents in the Senate -- Bernie Sanders of Vermont and Angus King of Maine -- but both caucus with the Democrats and are reliable Democratic votes.
It was not immediately clear whether Sinema would also caucus with the Democrats but she said she would not caucus with the Republicans.
"Becoming an independent won't change my work in the Senate," she said.
Sinema will need to avoid further antagonizing Democrats if she wants to retain coveted committee assignments.
Democratic Senator Chuck Schumer, the Senate majority leader, said Sinema had informed him of her decision to change party affiliation and asked him to keep her committee assignments.
"I agreed," Schumer said in a statement.
"Kyrsten is independent; that's how she's always been," he said."I believe she's a good and effective senator and am looking forward to a productive session in the new Democratic majority Senate."
- 'Work successfully with her' -
The White House also said it expected to continue to work with Sinema.
"Senator Sinema has been a key partner on some of the historic legislation President Biden has championed over the last 20 months," White House Press Secretary Karine Jean-Pierre said.
"We understand that her decision to register as an independent in Arizona does not change the new Democratic majority control of the Senate, and we have every reason to expect that we will continue to work successfully with her," Jean-Pierre said in a statement.
Democrats narrowly lost control of the House of Representatives to the Republican Party in the November midterm elections but picked up an extra seat in the Senate.
Sinema, a one-time member of the Green Party, was elected to the House as a Democrat in 2012 and to the US Senate in 2018.
She faces reelection in 2024 and several Democrats are already mulling a challenge to her in the party primaries.
US senators have occasionally switched parties before.The last to do so was Senator Arlen Specter of Pennsylvania, who abandoned the Republican Party for the Democrats in 2009.