What can Washington's primary tell us about the fight for the House majority?

Washington became known as the Evergreen State thanks to its bountiful evergreen forests. For election watchers, the state's downballot primary results have their own perpetual quality — they're often useful for anticipating what the November electoral environment will look like.

Since the early 1990s, Washington's primary vote for the U.S. House of Representatives has been a fairly reliable indicator for the direction of national electoral swings while also closely aligning with the outcomes in Washington's individual congressional races. This predictive value likely stems from both the timing and the format of the state's primary.

First, Washington's primary occurs not long before the general election — in September before 2007, and in August since then — so voters cast ballots in electoral conditions that are somewhat akin to those in November. And second, candidates in Washington have all run together in a single primary, regardless of party, under the state's old blanket primary system through 2002 and its current top-two primary since 2008 (with a brief hiatus in between). As a result, Washington's primary is more analogous to a general election — in which voters of all stripes choose among candidates from multiple parties — than a traditional party primary.

In the wake of the state's latest primary on Aug. 6, we now have numbers for 2024 to use in tandem with past data. Nationally, Washington's primary vote for the House suggests that we might see a shift back toward Democrats after the GOP won with a small edge in the 2022 midterms, potentially giving Democrats a path to a majority. But the road looks rocky for one Washington Democrat: The primary results also suggest that Rep. Marie Gluesenkamp Perez, arguably the most endangered incumbent House Democrat, will need to make up significant ground in November to win reelection.

Democrats could put the U.S. House majority in play

Dating back to 1992, the two-party vote share for major-party candidates in Washington's primaries — that is, excluding the small number of third-party and write-in votes — has tended to correlate with how the parties perform nationally in the general election. In 2020, Democrats won 57 percent in the state's primary and then garnered almost 52 percent of the national House vote, good enough to retain the majority they gained in 2018. But they lost ground in 2022, falling to 55 percent in the Washington primary and then garnering just shy of 49 percent of the national vote as the GOP flipped the House. Yet earlier this month, Democrats claimed 58 percent of the primary vote, an uptick from 2022 that could portend a slim advantage for the party in November.

This trend has repeated itself for most of the past three decades, whether under Washington's blanket primary system before 2004 or top-two primary dating back to 2008. For instance, the two-party vote share for House Democratic candidates in Washington fell from about 55 percent in 1992 to 49 percent in 1994. That November, Republicans captured the House for the first time in four decades and gained a whopping 52 seats as Democrats won just 46 percent of the national vote. Two years later in 1996, Washington Democrats won 53 percent of the primary vote, signaling potential November gains that were realized when the party won 50 percent of the national House vote (although that wasn't enough to reclaim the House majority).

Washington's primary has remained a useful predictor even as the state has become bluer in the Donald Trump era. Based on its presidential vote, Washington was usually 5 percentage points more Democratic than the country as a whole from 1992 to 2000 and roughly 10 points more Democratic from 2004 to 2012, but its lean has been around 15 points to the left since then. However, as the chart shows, the directional movement of the national House vote in recent years — more Democratic or more Republican — has continued to correspond with the swing in Washington's primary vote, even as the magnitude of such shifts has varied.

Even if Washington's 2024 primary does predict Democratic gains in the national House vote this November, though, winning a majority share of the national House vote doesn't guarantee Democrats will win back a majority of actual seats. That's because the relationship between a party's vote share and the number of seats it wins are not always in sync. While the broader electoral trends are felt in most districts, many other factors like candidate quality, incumbency, campaign spending and the idiosyncrasies of individual districts can produce results that in aggregate don't always line up with the national vote.

Plus, the House map is slightly tilted toward the GOP: Using The Downballot's (formerly Daily Kos Elections) district-level data based on the 2020 presidential race, the median House seat in that cycle — Virginia's 2nd District — sat about 2.5 points to the right of the country as a whole. Biden carried that seat by about 2 points but won the national popular vote by about 4.5 points (and Democrats won the national two-party House vote by around 3 points).

Gluesenkamp Perez faces an uphill battle

Washington's primary can give us some information about the national picture, but its unusual primary system is even more telling when it comes to how Washington's individual House races might play out. When we look at the primary vote totals for just Democratic and Republican candidates (again discarding the small number of third-party and write-in votes), the party vote shares in the 1992 to 2002 and 2008 to 2022 periods, the Democratic two-party vote share in a given contest has an extremely strong correlation with the Democrats' vote share in that district's general election. While there are typically small shifts — Democrats on average gained 1 percent in vote share from the primary to the general — changes like that would only matter in the tightest of races.

Of course, Washington may have one of the most highly contested elections in the country this cycle: The 3rd District in southwest Washington — held by Democratic Rep. Marie Gluesenkamp Perez — could be decided by the narrowest of margins this November. Another seat generally viewed as competitive is the 8th District east of Seattle — held by Democratic Rep. Kim Schrier — but it remains less likely to flip parties.

Looking at the primary results from earlier this month, Gluesenkamp Perez (the only Democrat on the ballot) won 47 percent of the two-party vote share in the 3rd District while Schrier and a couple of other minor Democratic candidates won 55 percent in the 8th District. Those percentages serve as something of a warning sign for Gluensenkamp Perez — and a reassurance for Schrier. Dating back to 1992, cases in which the incumbent party (usually with the incumbent running) won less than a majority of the primary vote have often portended defeat in November: In the 10 instances before 2024 where the incumbent party fell short of a majority, the party's candidate only won the general election twice. By comparison, in the 21 cases in which the incumbent party won 50 to 55 percent of the primary vote, that party lost in November just six times.

Gluensenkamp Perez won about 47 percent of the two-party vote share in her primary, leaving her about 3 points short of the 50 percent plus one vote mark that she'd need to win this November. As the table shows, candidates in her vicinity in past Washington races have all met defeat. Understandably, ratings outlets like Inside Elections, Sabato's Crystal Ball and The Cook Political Report all rank the 3rd District as a toss-up race. Tellingly, the two exceptions in the table followed primaries in which the incumbent party won just shy of 50 percent in the primary, at least 2 points better than how Gluesenkamp Perez did this year.

Still, Gluesenkamp Perez outperformed the expectations set by the primary in 2022 in a race that was truly an outlier. In the 3rd District primary two years ago, GOP candidates won a whopping 66 percent of the two-party vote because some independent and even Democratic voters cast ballots for Republican Rep. Jaime Herrera Beutler, one of only 10 House Republicans who voted to impeach Trump after Jan. 6. Yet Herrera Beutler narrowly finished in third place behind Gluesenkamp Perez and Republican Joe Kent, making her the first incumbent House member from Washington to lose in a primary since the advent of the top-two system in 2008.

Heading into the general election, the seat's red lean — Trump would have carried it by 4 points in 2020 — made it a long-shot Democratic pickup opportunity, and the 538 forecast gave Gluesenkamp Perez less than a 1-in-20 shot of winning. But remarkably, the Democratic vote share in November increased by more from the primary than any Washington race in the past three decades: Glusenkamp Perez improved her party's vote share by nearly 17 points from the primary to defeat Kent in the general election, 50.4 percent to 49.6 percent. As a result, the GOP's 66 percent vote haul in the 3rd District primary that year easily made it the highest percentage an incumbent party has won since 1992 only to lose in November, a testament to the peculiarities of a primary race that centered in large part on the future of a pro-impeachment Republican.

Nonetheless, Gluesenkamp Perez has to hope that lightning strikes twice to win reelection in 2024. Kent, who has had Trump's endorsement in both 2022 and 2024, is once more Gluesenkamp Perez's general election foe. That could mean some voters who were turned off by Kent in 2022 could again vote for Gluesenkamp Perez, although it's hard to know if she can repeat that feat in a presidential cycle with higher turnout. At the very least, though, she's given herself a huge resource advantage: As of July 17, Gluensenkamp Perez had raised a whopping $6.7 million, far ahead of Kent's $1.4 million. By comparison, the two candidates ran almost even in fundraising two years ago.

As for Schrier, she won just over 50 percent of this year's primary vote herself, while two minor Democrats brought the party total to about 55 percent, the party's best primary mark in the 8th District in the 1992-to-2024 period. Schrier actually won reelection in 2020 even after the Democrats fell slightly short of 50 percent in the primary, making her one of the two exceptions in the table above. But her 2024 primary performance could be a sign that the 8th District is moving out of the swingy cohort of seats and into a more clearly Democratic-leaning category. It's no wonder that the ratings outlets all view this as a likely Democratic seat — peripherally competitive but still unlikely to flip parties in November.

Ultimately, Washington's primary has shown predictive power over the past 30-plus years: The results from its primary in early August could point to Democratic gains in the House, but also Democratic difficulties in the Evergreen State's critically important 3rd District. Of course, when it comes to electoral history, past performance is no guarantee of future returns, and a range of uncertainty still surrounds the potential outcomes in November's hotly contested fights for control of individual seats in both Washington state and Washington, D.C.

CORRECTION (Sept. 4, 2024, 9:52 a.m.): This article originally said that former President Donald Trump carried Virginia's 2nd Congressional District by about 2 percentage points in 2020, putting it more than 6 points to the right of the country as a whole. President Joe Biden actually carried it by that margin in 2020, so the district was about 2.5 points to the right of the country.