The rate at which mail votes have been rejected for arriving late has ticked up in primaries this year and general elections last year in roughly a dozen states, prompting election officials to worry that the U.S. Postal Service is ill-equipped to deliver ballots in the fall midterms. The states studied by The New York Times include some of the most critical battleground House and Senate seats where control of Congress will be determined, as well as key races for governor and secretary of state. In Wisconsin, which hosts an open race for governor, a competitive House election plus contests for both chambers of the state legislature, lateness accounted for about 5,000 rejected mail ballots in the spring primary this year, or 78 percent of all tossed ballots.

During the last spring election, in 2023, the figure was roughly 2,300, or 47 percent of all tossed votes. The increase is particularly striking when comparing primaries in 2024 and this year. In Michigan’s primary earlier this month, more than 10,000 mail ballots were rejected for arriving after the state's deadline of 8 p.m. on Election Day.

That is nearly double the number of ballots rejected in 2024. In Washington, the number of late-arriving mail ballots increased from about 16,000 to more than 20,000 in the same period. The rise in rejected ballots comes at a time of immense upheaval at the Postal Service, where a budget crisis has prompted widespread complaints about delivery delays.

Roughly two dozen states sued the government over the president's executive order governing mail voting, which would require states to hand over voter information and would empower the Postal Service to block mail ballots from being sent or delivered in states that do not comply. In Colorado, Jena Griswold, the Democratic secretary of state, has rapidly increased the number of drop boxes across the state -- by 78 percent since 2018 -- so voters can return their ballots without concerns of postal delays or interference. The Postal Service countered claims that the agency has become unreliable by noting that over 95 percent of mail ballots have arrived on time in recent elections.