Kyrsten Sinema Brings Bad Tidings for Democrats in 2024

Arizona was on the cusp of seating a Democratic governor alongside two Democratic senators for the first time since 1951 when Senator Kyrsten Sinema abruptly announced last week she is leaving the Democratic Party to become an independent.

The move was met with harsh criticism from the left, which saw it as another in a series of self-aggrandizing acts that risk sacrificing the Democratic Party’s power and President Biden’s legislative agenda for her personal benefit.

Polls make it clear that Ms. Sinema is reviled by a large segment of her now-former party. In a recent Civiqs poll of likely voters, she was at a meager 7 percent approval among Arizona Democrats. Her switch to declare herself an independent may seem like a desperate act to hold on to the Senate seat she won in 2018 by fewer than three percentage points.

It may be that. But for Democrats looking ahead to 2024, her move compounds the difficulties of what is promising to be a brutal Senate map and suggests some hard truths about the party’s chances in Arizona and places like it.

The Donald Trump era may have given Democrats in Arizona a bit of a blue mirage. They were very successful in the midterms: Senator Mark Kelly won re-election, Secretary of State Katie Hobbs will be the new governor, and Adrian Fontes will become the secretary of state.

But it seems that the Democrats’ success is not simply the result of permanent shifts in Arizona’s demographics. Before Mr. Trump’s 2020 defeat, Arizona voted for five consecutive Republican presidential candidates and, before Ms. Sinema’s win in 2018, had not elected a single Democratic senator since 1976. Arizona’s electorate has certainly grown, urbanized and diversified, but registration percentages haven’t changed much since 2012. Today, 35 percent of Arizona registered voters are registered Republicans; 34 percent are Independents; and 31 percent are Democrats.

Democrats’ recent victories were presaged by overtly moderate Democratic candidates running against opponents endorsed by Mr. Trump. Ms. Sinema’s path to the Senate was buoyed by her opponent’s irreparably damaging association with Mr. Trump.

In announcing her departure from the Democratic Party, Ms. Sinema argued that representing Arizona as an independent will “provide a place of belonging for many folks across the state and the country who also are tired of the partisanship.” She is not wrong on that point: Over a quarter of Americans say they dislike both parties according to Pew Research Center. Only 6 percent said so in 1994.

For independent voters, it is disdain for partisanship — not moderate ideology — that drives most of them to buck the party label. A vast majority of independents, 75 to 90 percent, have no trouble identifying their preferred party, and they nearly always vote for it. It is the rancor and incivility associated with partisanship that dissuades independents from publicly showing their true colors.

Independent voters are hardly a uniform voting bloc: Generally, they just about evenly divide between those who hold liberal views and usually vote for Democrats and those who are conservative and usually vote for Republicans.

The bad news for Ms. Sinema — and perhaps for Democrats — is that independent candidates rarely succeed. Without a sizable Republican or Democratic base, an independent will struggle to cobble together ideologically incompatible voters who are bonded primarily by their reluctance to publicly identify with the party they secretly support.

This is one area where the Trump effect has come into play. In recent Arizona elections, the state’s independents have shown that they appear to be more favorable to Democrats than Republicans. In the state’s Senate race, exit polls suggest that independents backed Mr. Kelly over his Trump-endorsed opponent, Blake Masters, by 16 percentage points, and self-identified moderates favored Mr. Kelly by 30 percentage points. Ms. Hobbs similarly won the independent vote against her Trump-endorsed opponent, Kari Lake, by seven percentage points, and she won self-identified moderates by 20 percentage points.

Indeed, recent survey data I collected across Arizona shows that independents look much more like Democrats than Republicans when it comes to their disdain for Mr. Trump. Even among those Arizona independents who say they lean toward the Republican Party, 40 percent see the state G.O.P. as “too conservative.”

Given repeated Republican losses, it seems that Arizona Republicans — and independents, who have a large say in Arizona’s electoral outcomes — have rejected Mr. Trump as well as his chosen nominees, and this has helped usher in a wave of Democratic candidates, Ms. Sinema included.

When a state’s status shifts to swing, it is often attributed to demographic change in the electorate. But in Arizona, that is not likely the case, or at least that isn’t the full story. And this is why the outlook for Democrats might be troubling.

Sure, Arizona boasts high population growth in urban areas like Maricopa County. But voter data does not support theories that a transforming electorate is shifting electoral tides. Over time, voter registration percentages have shown Republicans declining slightly but maintaining their numerical advantage.

That shift is probably better attributed to changes in the politicians who are running rather than to the people deciding whether to vote for them.

If she had remained a Democrat, Ms. Sinema would not be the first politician who faced harsh criticism for frustrating her party, and many of them prevailed in subsequent elections. Senators Joe Manchin of West Virginia and Lisa Murkowski of Alaska are examples.

If nothing changes and Ms. Sinema runs for re-election, her former party will be left in a pickle. She probably can’t win as an independent, especially if her popularity doesn’t improve quickly, but a Democrat (like Representative Ruben Gallego, who has hinted at a Senate bid) running against Ms. Sinema and a Republican is also unlikely to win.

So for Democrats, Ms. Sinema has made a daunting Senate map in 2024 even worse. There will be 33 Senate seats up for re-election, and Democrats will defend 23 (including Ms. Sinema’s). Three of those seats are in states that Mr. Trump won by at least eight percentage points in 2020: Montana, Ohio and West Virginia.

When Republicans in Arizona and other states leave Mr. Trump behind, Democrats will lose this electorally useful foil. States where Democrats enjoyed upset victories against MAGA Republicans might see some of their gains rolled back, especially if the Republican Party rejects Mr. Trump and elevates candidates who better represent more of the party’s voter base.

Ms. Sinema’s move has just added another degree of difficulty to a formidable Senate puzzle for Democrats in 2024 — and beyond.

Samara Klar is a political scientist at the University of Arizona and an author of “Independent Politics: How Disdain for Parties Leads to Political Inaction.”

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