TOPEKA, Kan. — State and local election officials from across the country are warning that problems with the nation’s mail delivery system threaten to disenfranchise voters in the upcoming presidential election, telling the head of the U.S. Postal Service that it hasn’t fixed persistent deficiencies.

In an alarming letter Wednesday, the officials said that over the past year, including the just-concluded primary season, mailed ballots that were postmarked on time were received by local election offices days after the deadline to be counted. They also noted that properly addressed election mail was being returned to them as undeliverable, a problem that could automatically send voters to inactive status through no fault of their own, potentially creating chaos when those voters show up to cast a ballot.

The officials also said that repeated outreach to the Postal Service to resolve the issues had failed and that the widespread nature of the problems made it clear these were “not one-off mistakes or a problem with specific facilities. Instead, it demonstrates a pervasive lack of understanding and enforcement of USPS policies among its employees.”

The letter to U.S. Postmaster General Louis DeJoy came from two groups that represent top election administrators in all 50 states. They told DeJoy, “We have not seen improvement or concerted efforts to remediate our concerns.”

“We implore you to take immediate and tangible corrective action to address the ongoing performance issues with USPS election mail service,” they added. “Failure to do so will risk limiting voter participation and trust in the election process.”

The Postal Service on Wednesday reiterated DeJoy’s assurances that it’s well positioned to swiftly deliver election mail despite being in the midst of a network modernization that has caused some delivery hiccups. Mail is currently being delivered in 2.7 days on average, officials said.

The two groups, the National Association of Secretaries of State and the National Association of State Election Directors, said local election officials “in nearly every state” are receiving timely postmarked ballots after Election Day and outside the three to five business days USPS claims as the standard for first-class mail.

The letter comes less than two weeks after DeJoy said in an interview that the Postal Service was ready to handle a flood of mail ballots expected as part of this November’s presidential election and as former President Donald Trump continues to sow doubts about U.S. elections by falsely claiming he won in 2020.

Many voters have embraced mail voting and come to rely on it. And both Democrats and Republicans have launched efforts to push supporters to vote early, either in person or by mail to “bank” their votes before Election Day on Nov. 5.

Postal Service officials told reporters last month that almost 98% of ballots were returned to election officials within three days in 2020, and in 2022 the figure was nearly 99%. DeJoy said the Postal Service is better positioned to handle ballots than four years ago.

But officials in rural states have been critical of the Postal Service for years as it has consolidated mail-processing centers to cut its costs and financial losses.

The election officials warned that any election mail returned to an election office as undeliverable could trigger a process outlined in federal law for maintaining accurate lists of registered voters. That means a voter could be moved to “inactive” status and be required to take additional action to verify their address to participate in the election, the officials said in the letter.

Kansas Secretary of State Scott Schwab, the recent past president of the National Association of Secretaries of State, sent his own letter in recent days to DeJoy. He said nearly 1,000 ballots from his state’s Aug. 6 primary election couldn’t be counted because they arrived too late or without postmarks — and more continue to come in.

“The Pony Express is more efficient at this point,” Schwab posted on the social media platform X in late August.

Schwab and other Kansas election officials also have said some ballots arrive on time but without postmarks, which keeps them from being counted under Kansas law. What’s more, Schwab told DeJoy, local postal clerks have told election officials that they can’t add postmarks later even if it’s clear that the Postal Service handled the ballot ahead of the mail-in deadline.

Kansas will count ballots postmarked on or before Election Day if they arrive within three days.

In their letter Wednesday, election officials said colleagues across the U.S. have reported that Postal Service staff, from managers to mail carriers, are uninformed about the service’s policies for handling election-related mail, give them inconsistent guidance and misdeliver ballots.

“There is no amount of proactive communication election officials can do to account for USPS’s inability to meet their own service delivery timelines,” the officials wrote. “State and local election officials need a committed partner in USPS.”