President Donald Trump’s reported plan to terminate every member of the U.S. Postal Service Board of Governors and bring the independent and highly popular USPS under his administration’s control drew immediate outrage from the world’s largest postal union, which said the floated takeover would be illegal and destructive to public mail operations.

“Any attack on the Postal Service would be part of the billionaire oligarch coup, directed not just at the postal workers our union represents, but the millions of Americans who rely on the critical public service our members provide every single day,” said Mark Dimondstein, president of the American Postal Workers Union (APWU), which represents hundreds of thousands of current and retired postal workers.

The union leader’s statement came after The Washington Postreported Thursday that Trump is preparing to “dissolve the leadership of the U.S. Postal Service and absorb the independent mail agency into his administration, potentially throwing the 250-year-old mail provider and trillions of dollars of e-commerce transactions into turmoil.”

“Trump is expected to issue an executive order as soon as this week to fire the members of the Postal Service’s governing board and place the agency under the control of the Commerce Department and Secretary Howard Lutnick,” the Post reported, citing unnamed sources.

Lutnick, who was confirmed by the U.S. Senate earlier this week, is a billionaire with glaring conflicts of interest.

The Post noted that Trump has spoken publicly about the possibility of privatizing the USPS, which is currently led by Louis DeJoy. On Tuesday, DeJoy—who was initially nominated for the post by Trump and has worked to gut the Postal Service from within during his tenure—asked the USPS board to begin the process of finding his successor.

The new reporting prompted warnings that Trump, who lied relentlessly about mail-in voting in the run-up to and aftermath of the 2020 election, wants to disrupt ballot deliveries by bringing the USPS under his control.

“Trump’s reported outrage that the Postal Service was able to successfully deliver Americans’ mail-in ballots in 2020 is exceptionally alarming when considering the same man who helped incite an insurrection based on evidence-free election denialism now wants to be in control of millions of absentee ballots,” said Tony Carrk, executive director of the watchdog group Accountable.US.

“President Trump wants to consolidate power further and control access to your mail, all while making his wealthy donors richer in the process,” Carrk added. “All eyes should be on conservative senators who represent rural communities who will bear the brunt of postal privatization.”

Rep. Gerry Connolly (D-Va.), the top Democrat on the House Oversight Committee, said in a statement Thursday that privatizing the USPS would be “an attack on Americans’ access to critical information, benefits, and lifesaving medical care.”

“It is clear that Trump and his cronies value lining their own pockets more than the lives and connection of the American public,” said Connolly.

According to the Post, the USPS board was “planning to fight Trump’s order” and held an “emergency meeting” Thursday at which the board “retained outside counsel and gave instructions to sue the White House if the president were to remove members of the board or attempt to alter the agency’s independent status.”

“Two of the group’s GOP members—Derek Kan, a former Trump administration official, and Mike Duncan, a former chair of the Republican National Committee—were not in attendance,” the Post reported.

Dimondstein voiced support for the postal board’s plan to fight any Trump takeover attempt, saying the union backs all “efforts to defend our national treasure.”

“If this reporting is true, it would be an outrageous, unlawful attack on a storied national treasure, enshrined in the Constitution and created by Congress to serve every American home and business equally,” said Dimondstein. “The law created the postal board of Governors, and empowers it and it alone to hire and fire the postmaster general. Any effort by the administration to remove the board or fire postal executives is clearly illegal.”

“The Postal Service is owned by the people, for the benefit of the people. Postal workers are dedicated to our mission to serve, no matter who sits in the White House or in Congress,” the union leader added. “Postal workers and our unions will join with the public to fight for the vibrant, independent, and public Postal Service we all deserve.”