A late-night Supreme Court order could change the rules of the November election before many Americans realize what happened.

That is the warning from former federal prosecutor Harry Litman, who says the Trump administration’s emergency request involving mail-in voting contains the ingredients for what he calls an “October ambush.”

The legal maneuver began with an executive order President Donald Trump signed in late March. According to Litman’s analysis, the order would direct the Department of Homeland Security to create state-by-state lists of citizens considered eligible to vote.

The U.S. Postal Service would then be instructed to withhold mail ballots from voters whose names did not appear on those federal lists.

Nothing comparable currently exists.

The United States has no single federal citizenship roster governing election eligibility. Voter registration has traditionally been administered primarily by states under state and federal law, with Congress possessing constitutional authority to regulate aspects of federal elections.

Trump’s order would give the executive branch a powerful new role in deciding whose mail ballot moves through the postal system.

A federal judge blocked the policy in June. An appeals court upheld that injunction in July, preventing the order from taking effect while the underlying legal battle continued.

But on Monday, the Trump administration asked the Supreme Court to intervene on an emergency basis and lift the lower court’s order.

That request alarms Litman because it does not ask the justices to resolve the entire case after full arguments and ordinary briefing. Instead, it seeks temporary permission to enforce the policy while litigation proceeds.

The distinction sounds technical. Its real-world consequences could be enormous.

If the Supreme Court lifts the injunction close to the election, state officials, postal workers and voters could be forced to navigate a new federal system with little time to prepare. Eligible citizens omitted from a government list might not immediately know that their ballots had been blocked.

Litman warns that millions could potentially be affected, with the consequences falling especially heavily on voters who rely most on mail voting.

That predicted impact has not been established by a final judicial finding. It represents the legal expert’s assessment of what could happen if the order takes effect.

Trump has defended election restrictions by repeatedly alleging widespread voting by noncitizens. Noncitizen voting in federal elections is already illegal, and studies have generally found verified instances to be rare.

Supporters of the administration’s policy argue that citizenship verification strengthens trust in elections and prevents unlawful ballots. Critics contend that the order attempts to solve a marginal problem by creating a much larger risk: disenfranchising eligible Americans whose records are missing, outdated or mismatched.

The danger lies in administrative reality.

Government databases are not flawless. Names can change after marriage. Records may contain spelling errors. Citizens born abroad may have different documentation from citizens born inside the United States. Recently naturalized Americans might not appear immediately in every federal system.

Even small error rates could affect large numbers of people when applied to the national electorate.

Litman describes the potential result as “revolutionary and cataclysmic,” particularly because the executive branch—not the states or Congress—would assemble and police the eligibility list.

He also warns about timing.

Supreme Court emergency decisions can arrive quickly and sometimes contain limited explanation. If the justices act close to November, election administrators might have only weeks—or days—to respond.

That is why Litman uses the phrase “October ambush.” It would not be an ordinary campaign surprise based on a debate, scandal or unexpected political event. It would be a judicial intervention capable of altering how ballots are distributed just before voting concludes.

The administration has not yet won.

The lower-court injunction remains in place unless the Supreme Court lifts it. The justices could deny the emergency application, leave the order blocked or request additional briefing.

Even if they grant Trump’s request, that would not necessarily mean the executive order is ultimately constitutional. Emergency relief is provisional. Courts could later strike down the policy after fuller review.

But by then, critics fear, the midterm election might already be over.

That possibility places enormous pressure on a Supreme Court already facing public concern about its handling of emergency cases and election disputes.

The question before the justices is technically about whether the administration can enforce its order while litigation continues.

The question facing voters is more immediate: Could the federal government prevent their mail ballots from reaching them based on a citizenship list they have never seen?

Litman’s prediction may prove too dire. The Supreme Court may refuse to intervene, or safeguards could limit the policy’s impact.

But the emergency motion is now before the nation’s highest court, and the election calendar will not pause while the justices decide.

Trump’s order was stopped twice in the lower courts.

Now, with November approaching, he is asking the Supreme Court to remove the final barrier—and the answer could arrive when voters have almost no time left to react.