Senator Kyrsten Sinema of Arizona said on Tuesday that she would not seek re-election, ending more than a year of speculation about her political future and clearing the race for a traditional matchup between the eventual Democratic and Republican nominees.
“Because I choose civility, understanding, listening, working together to get stuff done, I will leave the Senate at the end of this year,” she said in a video announcement.
Ms. Sinema, a first-term senator who left the Democratic Party in 2022 to become an independent, faced potentially long odds in another race. Her decision to bow out of the race now sets up a showdown directly between Representative Ruben Gallego and the eventual Republican nominee. Kari Lake, the former nominee for governor — and a close ally of former President Donald J. Trump who has championed his baseless election fraud theories — is the leading candidate in the Republican primary, though Mark Lamb, a sheriff, is also running.
Though Ms. Sinema continued to caucus with Democrats after leaving the party and was a reliable vote for some parts of President Biden’s agenda, she angered Democrats by blocking efforts to raise taxes on corporations and aligned with a fellow centrist, Senator Joe Manchin III of West Virginia, to stop efforts to weaken the filibuster.
After winning a close 2018 contest over Martha McSally, a Republican, to become Arizona’s first elected female senator, Ms. Sinema, a calculated and charismatic politician, has had a dramatic tenure in Washington.
Her emphatic thumbs-down of an effort in 2021 to raise the minimum wage infuriated progressives, protesters have chased her through airports and activists have criticized what they say is her eagerness to side with business interests over the forgotten campaign promises she made to Arizonan voters. Arizona Democrats censured her after she declined to change the filibuster to pass voting rights legislation, and they said, essentially, that they were disappointed but not surprised when she left the party altogether.