A new analysis of 2024 voting data suggests that President Donald Trump’s effort to restrict mail voting could create a larger obstacle for Democratic voters than Republicans in several states expected to help decide control of Congress in 2026. Fair Fight Action, a Georgia-based voting-rights organization founded by former Democratic state Rep. Stacey Abrams, examined mail-ballot use in seven states that were presidential battlegrounds in 2024 or could feature competitive Senate races next year. The group found that Democrats cast mail ballots at higher rates than Republicans in several of those states. The differences did not change the outcome of any battleground state in the 2024 presidential election, all of which Trump won. But with both parties facing a narrow path to majorities in the U.S. House and Senate, even modest changes in how voters cast ballots could matter in close races. In Michigan, more than 2 million voters used mail ballots in 2024, according to the analysis. Democrats accounted for nearly half of those ballots, compared with 39% cast by Republicans — a Democratic advantage of roughly 200,000 votes. Michigan is expected to feature one of the Senate’s most closely watched contests in 2026. North Carolina showed a similar partisan pattern, though mail voting was less common. Democrats outnumbered Republicans among mail voters by about eight percentage points, while mail ballots made up approximately 5% of all votes cast in the state. The partisan gap was smaller in states where mail voting is more widespread. Arizona, where 83% of voters cast ballots by mail in 2024, gave Republicans a five-point advantage among mail voters, close to Trump’s 5.5-point statewide victory. In Nevada, where 44% of ballots were mailed, Democrats, Republicans and unaffiliated or other voters were represented at nearly equal rates. Lauren Groh-Wargo, Fair Fight Action’s chief executive, said Trump’s repeated claims that mail voting is fraudulent have weakened confidence in a method many voters previously used without partisan distinction. “Voting by mail is secure, convenient, and accessible,” Groh-Wargo said in a statement. She urged voters to choose a voting method and make a plan before the 2026 election. The White House has defended the proposed restrictions as election-security measures. Spokeswoman Lauren Bis said requirements such as voter identification and proof of citizenship should be viewed as commonsense safeguards, while arguing that Democrats should reconsider their reliance on voting methods if those measures affect their electoral prospects. Mail voting was broadly bipartisan before the 2020 election. A 2020 Stanford University study of six Western states that automatically mailed ballots to registered voters found no meaningful partisan effect on election results, though the system modestly increased turnout. The issue became more polarized during the COVID-19 pandemic, when many states expanded mail voting and Democrats were more likely than Republicans to avoid in-person voting. An analysis by the Massachusetts Institute of Technology’s Election Data and Science Lab found that Democratic voters used mail ballots at nearly twice the rate of Republicans in 2020, 60% to 32%. The difference narrowed in 2024, when the rates were 37% for Democrats and 24% for Republicans. Trump has repeatedly attacked mail voting, including during his 2020 reelection campaign and in a 2025 social-media post promising to lead an effort to eliminate mail ballots. His March 31, 2026, executive order directed the Postal Service to enforce new requirements affecting mailed ballots and cited public confidence and election integrity as reasons for the changes. The Postal Service is arguing in court that the requirements are limited technical specifications rather than election regulations. The Supreme Court is expected to decide whether the rule can take effect for this year’s midterm elections. If the restrictions survive, their effect could be felt most sharply in states where mail voting is common enough to influence close races but remains more popular among Democrats. That makes access to mail ballots not only a question of election administration, but potentially a decisive factor in the 2026 fight for congressional power.