Bennet, Hickenlooper, Colleagues Challenge Trump Efforts to Restrict Mail-In Voting

Sep 22, 2026 | Press Releases

261 current and former lawmakers joined together to file amicus brief in SCOTUS Mail-In Voting Case

Washington, D.C. - Colorado U.S. Senators Michael Bennet and John Hickenlooper, alongside the entire Senate Democratic Caucus and members of the U.S. House of Representatives, filed an amicus brief challenging the legality of President Donald Trump's executive order and U.S. Postal Service (USPS) rule that imposes unconstitutional, 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.

"Since the beginning of his administration, President Trump and congressional Republicans have done everything they can to make our voting system less safe and secure," said Bennet. "The Supreme Court must stand firm against this latest unconstitutional attempt to supersede the authority of states and Congress when it comes to our elections, all in an effort to make it harder for Coloradans to cast a vote by mail."

"Mail-in voting is safe, secure, and makes our elections more accessible," said Hickenlooper. "The Trump administration continues throwing everything at the wall to restrict the fundamental right of every American to choose their leaders. It's an unconstitutional, authoritarian attack that we won't let them get away with."

Colorado's vote-by-mail system helped produce a voter turnout rate of 71 percent in the 2024 general election, nearly 6 percent higher than the national average. Of these voters, 92.2 percent chose to return a mail ballot.

Nationally, nearly one-third of Americans have voted by mail in recent elections - a voting practice Trump himself used as recently as August 2026, when he voted in Florida's Republican primary.

In the court filing, the group argued that Trump's executive order and USPS's final rule violate the separation of powers and steal congressional authorities outlined in Article I of the U.S. Constitution, which gives the States and Congress exclusive authority over administering elections.

"As current and former legislators, amici took an oath to uphold and defend the Constitution of the United States - including its guarantee of the separation of powers," wrote the lawmakers. "The Constitution does not contemplate the Executive Branch acting unilaterally to assert power over federal elections. Yet that is what the Order and Final Rule do."

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 attack on this authority is an attempt to disenfranchise people who depend on mail-in ballots to vote.

"The integrity of our constitutional system depends on each branch keeping to its assigned role," concluded the lawmakers. "The Framers set up a two-part system that gave the States default authority to regulate federal elections subject to Congress's authority to override the States. The Framers did not provide the President with any authority to interfere in that system, nor has Congress subsequently imbued the President or the Executive Branch with any such authority by statute."

U.S. Representative Joe Neguse led the effort in the U.S. House of Representatives.

Bennet and Hickenlooper previously demanded that the USPS abandon this rule and have been staunch opponents of the Trump administration's efforts to restrict voting rights. Both senators also introduced the Mail and Absentee Voter Protection Act to nullify Trump's executive order.

Bennet is a member of the Senate Rules and Administration Committee with oversight over federal elections. In August 2026, Bennet demanded the Trump administration adhere to the National Voter Registration Act's "quiet period" that prohibits large-scale voter purges within 90 days of an election, pushing back against the Trump administration's ongoing voter suppression efforts. In April 2026, Bennet introduced the Mail and Absentee Voter Protection Act to block Trump's illegal and unconstitutional executive order that attacks Coloradans' ability to cast mail-in ballots. In April 2025, Bennet urged former USPS Postmaster General Doug Tulino to ensure on-time, reliable mail delivery to rural and mountain communities along the Western Slope and to prevent DOGE from exacerbating existing mail delivery issues in Western Slope communities. In June 2024, Bennet called on the USPS to improve mail delivery service for Colorado's mountain communities.

The full amicus brief is available HERE.

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