The Supreme Court’s decision on Monday to allow the Trump administration to move ahead with its plans to restrict mail-in voting threatened to introduce confusion into the midterm elections as states grapple with how to respond. The executive order at the center of the ruling directs federal agencies to create “state citizenship lists” of eligible voters. Those would be sent to state election officials and to the Postal Service, which could refuse to mail ballots for anyone whose name was not listed.

But some state elections officials and experts said on Tuesday it was unclear whether the new rules could be put in place by the November elections. Some states have already designed and printed ballots, a costly endeavor, and the first absentee ballots will be sent starting Sept. 4. At least one state, California, has already said it will sue again in the aftermath of the ruling. Other states, including Oregon and Colorado, signaled they expect voting to proceed as expected.

The Supreme Court ruling adds to a chaotic pileup of legal rulings and challenges. A coalition of Democratic-led states and Washington, D.C., challenged the new rule as unconstitutional, but the court said that move was premature. The Postal Service published a final rule on Friday, opening the door to new lawsuits. Jena Griswold, Colorado’s secretary of state, said the Supreme Court did not answer whether the executive order is unlawful, only whether lower courts weighed in too soon.

Democrats and voting rights groups argue the order violates the Constitution. President Trump has called mail-in voting “corrupt” despite voting by mail in Florida’s primary. Attorney General Liz Murrill of Louisiana called the ruling a “huge win for election integrity.”