At the end of a week when Democrats cinched 51-49 control of the Senate, Arizona Senator Kyrsten Sinema, who has served in the chamber as a Democrat, announced that she was reregistering as independent. The news was shocking only because of its timing; Sinema will continue be what she has long been—a uniquely cynical political careerist in a chamber that is not exactly short on cynicism or political careerists.

On paper, Sinema will now serve as “an Arizona independent.” In reality, Sinema’s move is a political gambit that formalizes her already close relationship with Big Pharma and the Wall Street interests that will serve as her political lifeline when she seeks reelection in 2024.

Sinema may have begun her political career 20 years ago as a Green Party–aligned critic of corporate power and previously identified as a “Prada socialist.” But those days are long gone, as Sinema has since abandoned her critique of capitalism and become a favorite senator of investment bankers, hedge-fund profiteers, and, most notably, the pharmaceutical companies that she has helped to thwart Democratic efforts to cut drug prices. Her latest move aligns her more thoroughly with the donors and special interests that she has so diligently represented since coming to the Senate in 2019, after a campaign in which she enjoyed massive financial and strategic support from Democrats.

Since the party took control of the chamber in 2021, Sinema has regularly undermined President Biden’s agenda. Her obstruction of Senate majority leader Chuck Schumer’s efforts to hold together the caucus for big votes—along with that of West Virginia Senator Joe Manchin—has infuriated the party base in Arizona. Grassroots activists recognize that Sinema’s not interested in helping Democrats get things done for working-class Arizonans because, as says Stephanie Taylor, a cofounder of the Progressive Change Campaign Committee, “Her constituency is Wall Street.”

A January Data for Progress survey of Arizona Democrats had Sinema losing the 2024 Democratic primary by 58 percentage points in a hypothetical primary contest with US Representative Ruben Gallego. Gallego was at 74 percent, while Sinema retained the support of just 16 percent of Democrats.

Gallego, who has not said whether he will run for the Senate, would have beaten Sinema in a primary. But with those kinds of polls, any number of prominent Democrats would have been positioned to defeat the senator, and to win in November in a state where the party just reelected Democratic Senator Mark Kelly and elected Democratic Governor Katie Hobbs.

Minutes after Sinema made her announcement, the grassroots “Primary Sinema” campaign that has been promoting an inside-the-party challenge to the senator explained that she was “bowing out of a Democratic primary she knew she couldn’t win.”

That’s true. But Sinema does not intend to give up her seat. The slick announcement video she released Friday morning and the sophisticated media strategy associated with it was clearly designed to position Sinema as a “maverick” who supports popular socially liberal positions, including abortion rights and LGBTQ+ rights, while veering toward the right on the economic issues where she has so frequently broken with the Senate Democratic Caucus. By every evidence, her plan is to run a big-budget reelection campaign that marginalizes the Democratic nominee—whoever that may be—and positions her as the only electable alternative for Arizonans who fear the election of a MAGA Republican senator.

There are no guarantees that the strategy will work. But it’s the only option left to her.

Sinema says she won’t caucus with the Republicans and claims that she doesn’t “anticipate that anything will change about the Senate structure.” In other words, she’ll seek to retain her committee assignments and, to do that, she will likely work within the framework of the Democratic Caucus—as do independents Bernie Sanders of Vermont and Angus King of Maine.

That’s vaguely good news for Democrats at the close of a week when the Georgia runoff victory of Senator Raphael Warnock gave the party a 51-49 advantage in the Senate that had been split 50-50. But Sinema will, undoubtedly, make things difficult, as she has during the current Congress, in which the Arizonan has frequently upended the Democratic agenda by stubbornly refusing to reject the obstructionist filibuster—even when it comes to issues where her position aligns with the party, such as protecting abortion rights.

While her stance on the filibuster may gave grabbed the biggest headlines, Sinema’s real focus in the Senate has always been on delivering for her big donors in general, and for the pharmaceutical industry in particular. In 2021, when she demanded that Democrats back off from their ambitious “Build Back Better” legislation, Politico reported, “Sen. Kyrsten Sinema (D-Ariz.) raised more campaign money in the last three months than in any quarter since she became a senator. And she hit that $1.1 million haul with a big assist from the pharmaceutical and financial industries, whose political action committees and top executives stuffed her coffers in the middle of negotiations on Democrats’ massive infrastructure and social spending bills.”

As early as 2020, Kaiser Health News explained how supporting the Arizona senator represented “a bet by drug companies that the 43-year-old Sinema, first elected to the Senate in 2018, will gain influence in coming years and serve as an industry ally in a party that also includes many lawmakers harshly critical of high drug prices and the companies that set them.” Today, Sinema’s campaign finance reports read like a pharmaceutical industry who’s who, with major money from donors associated with Eli Lilly, Pfizer, Merck, and industry groups such as the Biotechnology Innovation Organization. In 2021, during the fight over efforts to regulate drug prices, The Guardian headline read: “Big pharma has a powerful new shill, Kyrsten Sinema, fighting drug price reform.”

Sinema has sometimes backed modest reforms. But when it came to cracking down on Big Pharma in the most meaningful of ways, she has broken with the Democrats at the most critical of junctures.

In the fall of 2021, around the time that Salon reported Sinema and her allies had “effectively torpedoed their own party’s efforts to claw back more than $400 billion in prescription-drug costs for consumers and taxpayers,” Bernie Sanders said, “I get that the pharmaceutical industry owns the Republican Party and that no Republican voted for this bill, but there is no excuse for every Democrat not supporting it.”

Now that Sinema has identified herself as an independent, she will be making plenty of excuses. She’ll campaign as a centrist, with a strategy of scaring a lot of Democrats into grudgingly casting a ballot for her. In a three-way race with candidates of both major parties, she’s betting she will be able to flood the television airwaves with enough slick campaign ads to leverage sufficient support to pull it off. That’s a tall order. But she’ll have plenty of money from her real party, the party of Big Pharma and its Wall Street investors, to implement what is shaping up as the most cynical political strategy of 2024.