Here's Why Republicans Lost Their Advantage in the Electoral College

Former President Donald Trump defeated Vice President Kamala Harris across the country in 2024, winning the national popular vote by 1.5%—a 6-point improvement from his result against Joe Biden in 2020. Yet despite this seemingly comfortable national margin compared to recent elections for the GOP, Harris came pretty close to reaching 270 electoral votes, losing the tipping-point state of Pennsylvania by only 1.7%. As a result, Trump’s structural advantage in the Electoral College ended up at just 0.2%, meaning Harris would have needed to win the national popular vote by only 0.2% in order to claim the presidency.

This R+0.2% bias highlights a significant shift from the Electoral College’s biases in previous elections, which were R+2.9% in 2016 (when Trump beat Clinton despite losing the popular vote) and R+3.8% in 2020, reflecting a decline in the GOP's structural advantage in national electoral dynamics. One way to understand this contraction is to note that, although Trump’s overall national performance improved by about 6% in 2024, his margin only improved by 2.4% in the tipping-point state—amounting to a 3.6% leftward trend in Pennsylvania relative to the country.

Why did this happen? In simplest terms, Republicans have been trading heavily white suburban and exurban voters (who are overrepresented in today’s battleground states) for Hispanic and Asian voters clustered in places like Florida, Texas, New York, and California. Because none of those big states are core battlegrounds at this point in time, this new coalition proved much less electorally efficient for the GOP.

Below are the three primary reasons why the GOP’s structural advantage collapsed between 2020 and 2024—from a R+3.8% to just R+0.2%. I also estimate the share of that 3.6-point drop attributable to each factor.

1. Random Variation in State Partisan Leans

In 2020, the electoral map aligned extraordinarily well for Republicans, as a large number of medium-sized states ended up 2–5% more Republican than the nation. Of course, each state’s partisan lean relative to the country moves around from cycle to cycle. Controlling for the national environment, these state-by-state shifts have historically followed roughly a normal distribution with mean 0 and a standard deviation of 2.9%.

To see how much the GOP’s 3.8% bias might drop simply by normal flow of state partisan leans from cycle to cycle, we can perform a simulation using the 2020 results as a baseline. For each simulation, we add a single draw from a normal distribution with a mean of 0 and a standard deviation of 2.9% to each state’s partisan lean, recalculate the Electoral College outcome, and then find the tipping point state and the corresponding structural bias. We then average over all simulations to find the mean expected bias for 2024. The result is R+3.3%, which represents a drop of 0.5% from the initial 3.8%—despite 2020 Census electoral vote reapportionment alone suggesting a move from R+3.8% up to R+4.0%. Hence, purely random shifts among the states would have contributed roughly 0.7% toward shrinking the GOP’s Electoral College Bias edge, accounting for about 19% of the total decline (3.8% down to 0.2%).

2. Increasing Demographic Inefficiency of the GOP Coalition

After 2012, Republicans thrived in the Electoral College by winning over ancestrally Democratic, white working-class voters in crucial Northern states like Pennsylvania, Ohio, Wisconsin, and Michigan. Meanwhile, Democrats were piling up high margins in big coastal states—California, New York, Maryland, Massachusetts, Washington—where diverse urban cores and highly educated suburbs concentrated the Democratic vote.

However, this changed in 2024. Predominantly white areas, especially those with higher education levels, trended left. At the same time, Hispanic and Asian voters trended decisively to the right, fueling huge Republican gains in states such as Florida, Texas, New York, and California. However, those states were nowhere near the tipping point—making the GOP’s gains in them largely ‘wasted’ from an Electoral College perspective.

To estimate how demographic changes alone reduced the GOP’s advantage, I developed a county-level retrodictive regression model to predict 2024 results based on 2020 results and demographic data (including race, education, income, and population density). I then aggregated these county-level predictions into state-level projections. Overall, these retrodictions performed well, explaining 72% of the variance in state-level partisan lean shifts from 2020 to 2024. Using these state-level projections, I estimated a mean Electoral College bias of R+2.0% for 2024, both with and without the inclusion of a small amount of noise. By comparison, the “random-variation” simulation had already reduced the bias to R+3.3%. This additional drop to R+2.0% suggests that demographic shifts accounted for a further 1.3% reduction in the GOP’s advantage—representing approximately 36% of the total decrease in Electoral College bias from 2020 to 2024.

3. Non-Demographic Harris Overperformance in Battlegrounds

Harris generally overperformed the demographic model’s expectations in key swing states. Of the seven major battlegrounds, four ranked among her top six state-level overperformances. This pivotal dynamic neutralized much of the GOP’s remaining systemic edge, setting up a notable realignment in presidential politics.

One significant factor behind these battleground-specific overperformances was inter-state migration patterns, as detailed in a fantastic NYT piece by Ronda Kaysen and Ethan Singer. In states like Pennsylvania, Michigan, Wisconsin, and Georgia, new movers to the state were more Democratic than the populations they joined; in Arizona, however, new movers were 26% more Republican than existing residents. Across all seven battleground states (weighted by electoral votes), these incoming voters collectively leaned 6% more Democratic than their new neighbors. Harris underperformed the demographic model in Michigan (struggles with Muslim voters in Wayne County plus lingering problems in some white working-class areas) and in Arizona (GOP-friendly migration).

When I attempt to explain Vice President Harris’s resounding success in key swing states such as Georgia, North Carolina, Wisconsin, and Pennsylvania I come up with two primary factors. First, her campaign’s substantial financial advantage enabled a highly coordinated strategy that combined targeted advertising with robust ground operations, which proved particularly effective in these pivotal states. This advantage not only allowed for precise voter outreach but also contributed to improved Black voter turnout relative to 2020 in these key states, especially when compared to lower turnout in states such as South Carolina, Mississippi, and Alabama. This disparity highlights the strategic deployment of resources to mobilize key demographic groups in areas where their participation would have the greatest impact. Second, Harris’s supporters, who generally exhibited more moderate levels of enthusiasm compared to the fervor seen among Trump voters in polling, may have been especially motivated to turn out in battleground states. This heightened engagement likely stemmed from the perception that their votes would carry significant weight in determining the outcome of the election, underscoring the critical role of these states in shaping the broader electoral landscape. Either of these factors may be the entire reason, or maybe I’m missing something and there’s a third reason, but these are the two that comes to mind for me.

Overall, her net battleground overperformance was enough to drive the actual 2024 Electoral College Bias down to R+0.2%, rather than the R+2.0 predicted by demographics. This means that overperformance in key states beyond demographic expectations explains 50% of the total decrease.

Future of the Electoral College Bias

In 2024, the Electoral College advantage for Republicans hit a low point of R+0.2%. Yet one must note that the map aligned quite favorably for Harris, especially compared to 2020’s extremely GOP-friendly environment. If one assumes state-level random noise for each state partisan lean with mean 0 and standard deviation 2.9% for 2028, the projected bias moves higher to around R+0.6%, although any reversion of Harris’s state-specific overperformance could push it up more.

Then there is 2032. Modeling two cycles’ worth of random shifting (with an effective standard deviation of about 4.1% by 2032) suggests an expected GOP bias of about R+0.7 if we continued using the 2020-era electoral vote distribution. However, Republicans will benefit greatly from the 2030 Census reapportionment. States Trump carried in 2024 are currently expected to gain nine electoral votes on net, while Harris-won states will lose nine, worth roughly +0.7% in bias under present conditions. If the GOP begins the 2032 cycle at R+0.7%, the reapportionment effect will boost it to around R+1.4%.

At the same time, demographic trends may continue eroding this Republican advantage, particularly given that many decisive battlegrounds (like those in the Upper Midwest) remain heavily white and reasonably well-educated. Most analysts expect Democrats to keep gaining ground with white voters relative to the nation as a whole over the coming decade.

In short, after 2024’s extraordinarily tight outcome, the Electoral College bias for Republicans—once as high as 3.8%—is now much narrower. Future cycles will bring further state-by-state fluctuation, continued demographic changes, and reapportionment-induced realignments. Given those layers of volatility, neither party can bank on a sizable Electoral College advantage in cycles to come, but it is certainly possible that one develops.