‘Not a slam dunk’: Trump’s 2028 mail-vote push hinges on one big legal question

President Donald Trump faces legal uncertainty over whether his administration can put new federal mail-ballot rules in place ahead of the 2028 presidential election, legal experts told Fox News Digital.

The president issued an executive order in March directing the Postal Service to pursue new rules for federal mail ballots, including standardized ballot envelopes with an Official Election Mail designation and unique machine-readable barcodes. Per the order, the Postal Service would be empowered to turn away ballots that failed to meet its new standards, or those belonging to individuals who don’t appear on state-submitted lists of eligible mail voters.

On Sept. 14, the Supreme Court declined to lift a preliminary injunction blocking the rules from being implemented ahead of November’s midterm elections. Now, whether or not his changes can be implemented before the 2028 election looms large over Washington.

Experts who spoke to Fox News Digital argued that the ruling will hinge on how the Supreme Court parses competing claims to authority between the executive branch’s ability to regulate mail and the right of states to administer elections however they see fit.

USPS WOULDN'T DELIVER BALLOTS IN STATES THAT REFUSE TO FORK OVER MAIL-IN VOTER INFO UNDER PROPOSED RULE

US President Donald Trump displays a signed executive order in the Oval Office of the White House in Washington, DC, US, on Tuesday, March 31, 2026. Trump signed an executive order Tuesday intended to make it harder for voters to cast mail-in ballots, escalating his long-running campaign against a practice used by millions of Americans. (Aaron Schwartz/CNP/Bloomberg via Getty Images)

"​​If the Court views this primarily as an attempt by the President to regulate federal elections, the Court is likely to invalidate it," Florida State University law professor Michael Morley told Fox News Digital. "The President has no constitutional authority over federal elections and Congress has not delegated him broad statutory authority over the field."

If the Supreme Court views the case through another lens, however, Morley says that could change things.

"In contrast, the Court may instead view the new rules primarily as administrative requirements for the post office to ensure efficient operations and protect the integrity of the [mail]," he said. "Viewed from this perspective, the rule would be viewed as a much more prosaic matter and likely be upheld. It would be remarkable for the Court to conclude the Postal Service lacks authority to regulate the process through which millions of parcels of important (i.e., election-related) mail are submitted for delivery."

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President Donald Trump, left, and an absentee ballot for the 2020 U.S. election. A federal judge on Tuesday blocked the U.S. Postal Service from implementing part of Trump's executive order tightening mail-in voting rules ahead of the 2026 midterm elections. (Getty Images)

The Supreme Court ruled by a margin of 7-2 to uphold the injunction preventing Trump’s executive order from being implemented ahead of the midterms. Justices Clarence Thomas and Samuel Alito dissented, while Justice Brett Kavanaugh voted to uphold the injunction, noting that, though the Post Office may have the authority to implement such a regulation, forcing its new rule to be implemented so close to an election likely runs afoul of federal law.

Some have attempted to use the ruling to predict how the court will ultimately rule on the merits of the Post Office’s ability to regulate election-related mail.

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Absentee envelopes (Getty Images)

"At least six justices seem to think that the administration will lose on the merits," Stephen Richer, a legal fellow at the libertarian Cato Institute, told Fox News Digital. "The Constitution doesn't vest authority to regulate elections to the president and I think that they would say that this effectively dictates how elections can be run."

"The Constitution delegates brought authority to the Congress and to the states to administer elections. And having this requirement sure seems like an additional requirement for administering mail voting elections," Richer, who was formerly a Republican election official in Arizona, continued.

Others, however, see the court’s ruling as primarily a procedural consideration rather than a proper rebuke of the administration’s efforts to regulate mail voting.

"Justice Kavanaugh, whose vote decided this outcome, was explicit that he believes the Postal Service likely has the statutory authority to require verified voter lists and tamper-resistant envelopes for federal ballot mail," America First Policy Institute senior legal fellow Chad Mizelle told Fox News Digital.

"He concluded there simply wasn't enough time left before the midterms to implement the rule responsibly. That's a timing question, not a ruling on the underlying law," Mizelle, who recently served as the chief of staff at the Justice Department, added. "What's at issue here is pretty basic: verified voter lists and tamper-resistant envelopes for ballot mail. The kind of chain-of-custody standards most people would assume already exist for something as important as a ballot."

Regardless of what the Supreme Court’s decision ultimately means for the rule’s future, the president has characterized the injunction blocking its implementation in the 2026 elections as a major defeat.

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"Republicans just got another bad decision from the United States Supreme Court, one that the Court System took forever to give, and then blamed it, in part, on no time left to implement a solution to our totally CORRUPT and out of control Mail-In voting ‘disaster,’" the president wrote on Truth Social shortly after the court handed down its decision. "It is a big loss for Republicans, and America itself, and makes cheating by the Radical Left ‘Dumocrats,’ on Mail-In Ballots, a much easier thing to d."

There have been individual cases of election and mail-ballot fraud, but they do not show that widespread fraud is occurring across U.S. mail voting.

If the president is right about the impact of his mail voting rule, however, that leaves a big question mark on the board as Election Day approaches.

"It's an interesting issue. It's not a slam dunk," ​​Ilya Shapiro, a former law professor and current senior fellow at the right-leaning Manhattan Institute, told Fox News Digital. "And it's not about whether mail voting is good or bad. It's about who gets to set the rule for it, whether it's the state, Congress, or federal agency acting under general postal statutes that are quite broad."

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The White House did not respond to a request for comment when reached by Fox News Digital on Friday.