A Detailed Analysis of California’s (Maybe) New Congressional Map
August 21, 2025 · 1:49 PM EDT
If you thought the midterm elections wouldn’t start until 2026, think again. Control of multiple House seats will now effectively be decided this fall.
The California Legislature is soon expected to advance a new congressional map for the Golden State that is heavily biased in Democrats’ favor. It’s the party’s first move in the mid-decade redistricting arms race that broke out when President Donald Trump, seeking to tilt the House playing field in Republicans’ favor, pushed for a redraw of Texas’s congressional map that would likely flip several seats from blue to red.
That map is currently making its way through the Texas Legislature, but California Democrats’ task is harder. The Golden State has an independent redistricting commission that is enshrined in the state constitution, so the legislature can’t simply pass a new map on its own. Instead, the measure it passed this week is a state constitutional amendment that would temporarily override the commission’s map for the 2026, 2028, and 2030 elections. But in California, state constitutional amendments need to be approved by voters, so this resolution will trigger a special statewide election on November 4 in which voters will have the final say on whether the legislature’s map goes into effect.
If the referendum passes, the revised map would turn three reliably red seats into reliably blue ones and make two Republican-held seats much easier for Democrats to flip, parrying the effects of the proposed Texas map with almost eerie similitude. Democrats need a net gain of three seats nationwide to win a House majority in 2026, so changes in even a handful of districts can be significant. Here at Inside Elections, we won’t be issuing ratings for the new districts until the new map officially passes (if it even does), but here’s a detailed analysis of the changes to the districts’ partisan composition.
Overview
Make no mistake about it: The proposed map is an aggressive Democratic gerrymander. One way of measuring the bias of a congressional map is called “efficiency gap,” or the difference between how many votes the map “wastes” for one party versus the other. (For our purposes, any vote cast for the losing party in a district, or cast for the winning party after it already won a majority, is wasted.) Based on the results of the 2024 presidential election, the proposed California map has an efficiency gap of D+20. By contrast, the current, commission-drawn map has an efficiency gap of D+8, indicating a modest Democratic bias. (The ideal efficiency gap is 0, but small deviations on either side are often inevitable.)
Furthermore, 46 of the 52 districts in the proposed map are bluer than D+5, according to Inside Elections’ Baseline, our measure of the baseline partisanship of states and congressional districts. Just four districts are redder than R+5, and just two districts fall in the competitive zone between D+5 and R+5. Under the current map, just 37 districts are bluer than D+5, while eight districts are redder than R+5 and seven districts are in the middle. So not only would the proposed map turn some seats from red to blue, but it also shores up multiple swing districts for Democrats and makes them more difficult for Republicans to win.
District By District: Northern California
The proposed map’s changes start with the 1st District, currently a collection of inland Northern California counties represented by GOP Rep. Doug LaMalfa. This district currently has an R+26 Baseline, but the new map would move it all the way to D+11 by adding a number of dark-blue counties currently represented by Democratic Reps. Jared Huffman and Mike Thompson. (Their districts each get about 20 points redder as a result, but they were already so blue that the pair are still not in any electoral danger.) This makes the 1st District the seat that shifts the most under the proposed lines.
Democrats would have carried the new version of the 1st in every statewide election since at least 2016, making this the map’s first all-but-guaranteed Democratic pickup. State Senate President Pro Tempore Mike McGuire would be a likely candidate for this new seat, which KCRA reports was drawn “specifically for him in exchange for his support of the redistricting plan.” Audrey Denney, who ran against LaMalfa in 2018 and 2020, also says she would run here if the map passes.
The second probable Democratic pickup under the proposal is Republican Rep. Kevin Kiley’s 3rd District, currently an R+9 seat that runs along the Nevada border. The new version of the district has a tendril that reaches into Sacramento and adds thousands of Democratic voters from Democratic Reps. Ami Bera’s and Doris Matsui’s districts. The new 3rd District has a Baseline of D+6 as a result; the only Republican to carry it in the last decade was Lanhee Chen in the 2022 controller’s race. Reportedly, Bera is actually considering running in this district rather than sticking with his current 6th District, which would move from D+13 to D+6 if the new changes take effect. Navy veteran Kermit Jones, who ran against Kiley in 2022, could also run in the redrawn 3rd, and Nevada County Supervisor Heidi Hall is already running.
Most other Northern California districts see little change under the proposed map; for instance, all the seats in the San Francisco Bay Area remain safely Democratic. However, Democratic Rep. Josh Harder’s 9th District, based in San Joaquin County in the Central Valley, would become significantly bluer by taking in parts of the heavily Democratic East Bay. It would move from D+3 to D+17 as a result, taking it completely off the board for Republicans.
District By District: Central California
California’s 13th District, a Hispanic-majority seat in the Central Valley, was the closest House race in the country in 2024, but the new map would give Democratic Rep. Adam Gray some breathing room. The proposal adds the city of Stockton to the district, pushing it from an evenly divided Baseline to D+6. However, as Latino voters have shifted right in recent years, this district has gotten better for Republicans; while former President Joe Biden would have carried it by 18 points in 2020, former Vice President Kamala Harris would have carried it by only 1 point in 2024. So even if the new map passes, Gray would likely still have to work to get re-elected. Former Stockton Mayor Kevin Lincoln, who lost a close race for the 9th District in 2024 and recently launched another bid for that seat, would consider shifting to running in the 13th, where Republicans have so far struggled to recruit a top-tier candidate.
Further down Interstate 5, Republican Rep. David Valadao’s 22nd District would move from D+2 to D+7 under the new lines. That would make it easier for Democrats to dislodge Valadao, who has frustrated them for years by overperforming the top of the ticket. But this district, too, is trending Republican; it would have voted for Biden by 17 points in 2020 but Trump by 2 points in 2024. Expect this district to remain a battleground in 2026 regardless of the map.
Other Central California districts wouldn’t change too much under the new map. Democratic Rep. Jim Costa’s Fresno-based 21st District would get slightly bluer, going from D+8 to D+10, and could be in play in the future if Latinos continue to move rightward. (Republican strategists are excited about Army and Marine veteran Lorenzo Rios, who declared against Costa last month.) And notably, Reps. Tom McClintock and Vince Fong are the rare Republicans whose districts (the 5th and 20th) remain intact under the plan.
District By District: Southern California
Most districts in the Los Angeles area are dark blue under the current map and would remain so under the proposed one. However, there are a few changes worth noting. Democratic Rep. George Whitesides, who defeated former Republican Rep. Mike Garcia in a competitive race in 2024, would have a clearer path to re-election under the new plan: His 27th District would go from a Baseline of D+3 to D+11 after trading some redder parts of Los Angeles County for some bluer ones.
The new map would much more dramatically reconfigure the 41st District, which would retain nothing except its number. The current version of this seat, represented by Republican Rep. Ken Calvert, is an R+7 district spanning Riverside County. The proposed version is a D+16 seat in eastern Los Angeles County that would be a near-automatic pickup for Democrats (their third, if you’re keeping score).
It would come at a cost for Democrats, though: The proposed map adds the Republican core of the old 41st District to the adjacent 40th District, currently a swing district represented by GOP Rep. Young Kim. As a result, the 40th goes from an R+9 seat to an R+17 seat, locking it in for Republicans. Which Republican, though, is an open question. If the new map passes, this seat could see a member-versus-member race between Kim and Calvert. According to data from The Downballot, Calvert currently represents 51 percent of the proposed 40th, while Kim represents 32 percent. However, as RRH Elections notes, Kim would likely appeal more to non-Republican voters if California’s top-two primary system shuts Democrats out of the general election.
The proposed map also gives small boosts to three Orange County Democrats. Rep. Derek Tran’s 45th District adds a few more Democratic areas of Los Angeles County to go from D+1 to D+5, although it should remain competitive; the Republican candidates for attorney general, controller, and treasurer in 2022 all would have carried the new version of this seat. Rep. Dave Min’s 47th District grows from D+2 to D+6 by offloading Republican areas such as Huntington Beach (which the new 42nd picks up, moving from D+38 to D+10 in the process). Finally, Rep. Mike Levin’s 49th District ticks up from D+3 to D+6.
The last Republican incumbent that the proposed map endangers is Republican Rep. Darrell Issa. Issa’s 48th District, which currently has a Baseline of R+20, would become almost exactly evenly divided by adding large chunks of heavily Democratic Palm Springs and San Diego. Issa could have trouble holding on here in a Democratic-leaning midterm environment, and a number of prominent Democrats could run, including Brandon Riker, who is currently challenging Calvert in the 41st District; Ammar Campa-Najjar, who ran against Issa in 2020; and Marni von Wilpert, a San Diego city councilmember.
Finally, two districts in inland SoCal saw only minor revisions under the new map. Republican Rep. Jay Obernolte would be the fourth and final safe Republican under the new map; his 23rd District goes from R+18 to R+21. And on the surface, the Baseline of the 25th District, a Hispanic-majority seat represented by Democratic Rep. Raul Ruiz, remains constant at D+9. However, mapmakers made some tweaks that could insulate Ruiz from danger if Latinos continue to move toward Republicans — namely, adding more of the Palm Springs area, which is moving toward Democrats.
What’s Next
Again, though, all of this would only come to pass if California voters approve the new map via referendum in November — and that’s far from a given. Americans really don’t like gerrymandering, even when their own party does it. According to an August poll from YouGov/The Economist, 66 percent of Americans said they would prefer congressional districts in their state to not give an advantage to either party; only 22 percent of Democrats said they should be drawn to favor Democrats, and 31 percent of Republicans said they should be drawn to favor Republicans. And in California specifically, a July 28-August 12 poll from Politico/Citrin Center/Possibility Lab found that 64 percent of registered voters supported keeping the state’s independent redistricting commission, while only 36 percent wanted to put the state legislature back in charge of drawing the lines.
But Democrats, led by California Gov. Gavin Newsom, hope to overcome that sentiment by casting the referendum as a counterbalance to Republicans’ own efforts to gerrymander other states. If the special election turns into a proxy war over which party should control the House after 2026, it could pass simply because California is so Democratic; ditto if the election turns into a fight over Trump’s anti-competitive maneuverings in a state where 68 percent of Californians disapprove of the president. Internal polling should always be taken with a grain of salt, but KCRA reported that Democratic polling found that Californians supported the referendum, 52-41 percent, when told it “adopts temporary congressional district maps if Texas or other states redistrict mid-decade” and “declares state policy supporting nonpartisan redistricting commission nationwide.” A leaked memo from Newsom’s longtime pollster, David Binder Research, also claims that voters supported the referendum 57-35 percent, but, crucially, we don’t know how the question was worded or whether it was an informed ballot test.
As these examples show, polls on issues this nuanced can often diverge wildly depending on how pollsters ask the question — and, often, it’s not even clear what is the “right” way to ask. So it’s impossible to say whether the referendum will pass based on the spotty information we have now. The only thing we can say with any certainty is that, given the stakes, hundreds of millions of dollars will be spent over the next 10 weeks to frame the terms of the debate.