WASHINGTON, D.C. – U.S. Senator Tammy Baldwin (D-WI) and her colleagues are urging the U.S. Supreme Court to block President Trump’s unconstitutional Executive Order and U.S. Postal Service rule that attempts to restrict Wisconsinites’ ability to vote by mail ahead of the 2026 midterm elections. 

Specifically, Baldwin joined a bipartisan group of 261 current and former lawmakers in filing an amicus brief with the U.S. Supreme Court in the matter of State of California, et al. v. United States Postal Service, et al., a lawsuit brought by a coalition of State Attorneys General against the U.S. Postal Service (USPS). The court case challenges a final rule issued by the USPS in response to Trump’s directive that imposes unconstitutional and unworkable restrictions on mail-in voting, including requiring states to provide a “citizenship verification list” and attempting to give USPS control over who can vote by mail.

“The President is trying to meddle in the elections because he knows that Americans are going to hold him accountable in November,” said Senator Baldwin. “Instead of changing course and doing what he said he would to lower costs, he is trying to silence Americans from having their voice heard at the ballot box. This effort to stop Americans from voting by mail – despite many Wisconsinites already having their ballots on their counters – is cut and dry unconstitutional, and the Supreme Court needs to say just that and protect Americans’ right to vote.”

Nearly one-third of Americans have voted by mail in recent elections, including over 500,000 Wisconsinites in the 2024 election — a voting practice Trump himself used as recently as August 2026, when he voted in Florida’s Republican primary.

In the court filing, the lawmakers argue that Trump’s Executive Order 14399 and USPS’s final rule violate the separation of powers and usurp congressional authorities outlined in Article I of the U.S. Constitution, which gives the States and Congress exclusive authority over election administration.

The lawmakers also pointed to a recent federal court ruling blocking the USPS from implementing its newly finalized mail ballot rule for the midterm elections, saying the agency lacked the authority to implement the rule and that its actions are “substantively unconstitutional and contrary to law.”

The lawmakers concluded by asserting States’ power to administer elections and Congress’s power to make or alter rules regulating elections, which the Supreme Court itself has described as an “override” authority. Trump’s illegal incursion on this authority is an attempt to disenfranchise people who depend on mail-in ballots to vote.

Senator Baldwin has repeatedly pushed back against the Trump Administration’s efforts to restrict mail-in voting and disenfranchise Wisconsin voters. In June, Baldwin demanded that the USPS abandon the rule, and in July, she called on the USPS to immediately address severe mail delays that caused hundreds of Wisconsinites’ ballots to arrive after Election Day in April.

The lawmakers’ demands come as President Trump has taken an all-of-the-above approach to try to interfere in the upcoming 2026 elections. In addition to his attempt to curtail legal mail-in voting, the President has repeatedly threatened to send federal agents to states’ polling places, repeated his claim about “rigged” elections more than 100 times, and sent FBI agents into Milwaukee to relitigate his 2020 election loss.

The amicus brief was led by Senators Alex Padilla (D-CA), Chuck Schumer (D-NY), Dick Durbin (D-IL), and Gary Peters (D-MI) and joined by the entire Senate Democratic Caucus.

The full brief is available here.

An online version of this release is available here.