Senate Democrats sparred with Postmaster General David Steiner on Wednesday over the U.S. Postal Service’s move to stop delivering mail-in ballots in states that don’t hand over their voter rolls to the federal government.

Steiner, who has stayed out of the political spotlight since taking the lead role at USPS last year, was grilled by Democrats about the entity’s decision to follow President Donald Trump‘s executive order, functionally establishing a national voter verification system for mail-in ballots. In late May, USPS proposed a rule that would create a “Mail-In and Absentee Participation List” in line with Trump’s executive order request, if approved.

Sen. Elissa Slotkin, D-MI, bashed Steiner for the rule proposal, calling Steiner a “pawn” in the Trump administration’s “authoritarian playbook.” Sen. Gary Peters, D-MI, ranking member of the Homeland Security and Government Affairs Committee, also slammed the postmaster general for following the executive order.

“There’s no federal law that the postal service is authorized to create these types of voter databases, ballot verification systems, or mandatory standards — it just simply doesn’t exist,” Peters said. “Just because President Trump wants to do this does not make it law, doesn’t make it right, doesn’t make it constitutional.”

But Steiner backed the rule proposal, saying it was in line with long-standing recommendations from the Postal Service. Steiner focused on the aspect of the rule proposal and executive order that would create a unique barcode and envelope for each individual mail-in ballot. He said that the rule is “not a political question, it’s a question of how do we most efficiently and securely move ballots.”

“That is what our proposed rules suggest: that we have a unique barcode, a unique envelope,” Steiner said. “That is not something that is new. That’s something that’s been being used by states throughout the country on both sides of the political spectrum. So, California has followed it, Oregon has followed it, Arizona has followed it, Florida has followed it, among many other states.”

Under the proposed USPS rule, each state would first hand USPS a list of voters submitting mail-in ballots for that election, along with each voter’s corresponding personalized barcode on their ballot. Then, the USPS would return a final “Mail-In and Absentee Participation List” to each state’s chief election official to finalize the names of all enrolled voters in the state and the barcodes associated with their ballots.

When Peters pressed Steiner on whether USPS would still deliver mail-in ballots to a state if it hypothetically refused to turn its absentee voter list over to the federal government, Steiner replied, “No.” Peters then fired back, saying the rule essentially “coerces” states into conforming to the executive order.

“The states control their own elections, that’s pretty clear in the Constitution,” Peters said. “And an effort by this administration to nationalize elections and have the federal government having this information is incredibly dangerous precedent. You can imagine sharing this information with the Department of Homeland Security, using this, these lists for a variety of nefarious purposes.”

Colorado remains among the states declining to follow Trump’s orders, with Secretary of State Jena Griswold reiterating that she will not provide voter information to the Trump administration.

Democrats have challenged Trump’s executive order on mail-in ballots in court, arguing that submitting voter rolls to the federal government is inconsistent with federal voting rights laws. As Democratic plaintiffs appeal a judge’s prior denial of their injunction request against the mail-in voting executive order, the USPS rule proposal remains in legal limbo.

But Democrats weren’t the only ones to spar with the postmaster general. One Republican senator, Sen. Josh Hawley, R-MO, fumed at Steiner during a spat that started over Hawley raising concerns about a pile of dumped, undelivered general mail found in his state. Steiner said he was “outraged” by the image of the pile, but that it was his first time hearing of the issue.

Hawley then questioned the leadership at USPS, asking Steiner if he would “refuse bonuses so long as the mail goes undelivered.” When Steiner did not answer Hawley directly, the senator said, “You are in charge of the postal service, and we have given you everything you’ve asked for.” The interaction escalated when Steiner began laughing, attributing his giggles to Hawley’s assertion that Congress has given USPS everything while the service remains underwater financially.

“If things don’t get better, you ought to resign because you’re not doing the job,” Hawley said.