But Sinema does not seem rattled by any of it—and it’s not clear that she should be. Unseating her would be difficult. She isn’t up for reelection until 2024, so any primary challenge is years away. Voters’ memories are short, and the political landscape will be different by then. Ousting a sitting senator is a dubious project, and even if lefties were to defeat Sinema with one of their own, a more progressive candidate might find it harder to win a general election. Arizona is still a purple state, and Sinema’s popularity among independents and Republicans remains fairly high. “I’ve seen [progressives] throw everything at her to create this narrative that she’s in this very perilous situation,” Mike Noble, the research chief at the Arizona-based nonpartisan polling firm OH Predictive Insights, told me. But “I don’t see a need for her to be hitting the panic button.”…

Another Democrat could challenge Sinema in 2024 and win. That person would have to be similarly well known, with plenty of money and optimism to spare: Winning a primary challenge against an incumbent senator is extremely difficult; only five people have done it this century, according to FiveThirtyEight. Four of those five went on to lose the general election. (And Sinema’s state is more difficult terrain for Democrats than any of those primary victors’ states were.) If another Democrat did win the nomination over Sinema, they might struggle in the general. The new candidate’s fate would depend, in part, on the GOP nominee: a Donald Trump type could turn off Arizona’s Mormon community and suburban voters; a more moderate candidate could win them over.

Sixteen percent of Republican women in Maricopa County, where most Arizonans live, broke with their party to vote for Sinema in 2018, making her the first Democrat to win a Senate race in the state in 30 years. I wrote about some of those women then—and I called them up again for this story. Jane Andersen, a former Republican, told me that Sinema represents the interests of moderates. “She was elected in a state that has extreme conservatives and a lot in the middle,” Andersen said. “She’s doing a fantastic job.” Relying on conservative and independent voters to build a Democratic majority in the Senate always carried the risk that, when push came to shove, those voters wouldn’t go along with Democrats’ goals. I recognized a little bit of Sinema in these women—an eagerness to buck expectations. “Censure and threats from one’s party can be a badge of honor,” Laura Clement, an ESL teacher and independent voter from Mesa, told me in an email. “She’s powerful, and I want to keep people like her in power.”