The Trump administration on Monday took a new chance to bash the Consumer Financial Protection Bureau’s push to restrict arbitration agreements, saying the regulation—already facing challenges in court and on Capitol Hill—will only put money in the pockets of plaintiffs lawyers.

A U.S. Treasury Department report, published Monday, brought an additional voice into the effort to undercut the rule, which Republican lawmakers and the President Donald Trump-appointed temporary head of the U.S. Office of the Comptroller of the Currency have criticized for the costs it would force the financial industry to bear. Those critics, drawing from the CFPB’s arbitration study, have also argued that class actions bring meager relief to aggrieved consumers while arbitration provides a low-cost, efficient alternative to resolve disputes.

“The rule will effect a large wealth transfer to plaintiffs’ attorneys,” the Treasury Department report said. “On average, plaintiff-side attorneys’ fees account for approximately 31 percent of the payments that plaintiffs receive from class action settlements—and in many types of cases, much more. In an average case, plaintiffs’ attorneys collect more than $1 million; actual plaintiffs receive $32 each. The bureau’s data indicate that the rule will transfer an additional $330 million over five years from affected businesses to the plaintiffs’ bar.”

Against an onslaught of attacks, CFPB Director Richard Cordray has repeatedly defended the arbitration rule—a regulation that is sure to go down as the most sweeping and significant of his tenure leading the Obama-era watchdog agency. In August, Cordray took to the op-ed pages of The New York Times to argue that consumers should have the power to sue banks.

On Monday, CFPB spokesman Sam Gilford said the Treasury Department report “rehashes industry arguments that were analyzed in depth and solidly refuted in the final rule.” Mandatory arbitration clauses, he said, cost consumers billions of dollars by blocking group lawsuits.

“Banks, credit unions and other companies file class action lawsuits to pursue justice when they are harmed as a group, and our rule restores consumers’ right to do the same. The Equifax and Wells Fargo cases show how important it is for consumers to be able to band together to take legal action together,” Gilford said. “This report and similar industry analyses fail to make the case for allowing companies to continue using these clauses to deny consumers their day in court.”

Since the summer, Cordray and Keith Noreika, the Trump-appointed acting U.S. Comptroller of Currency, have engaged in a war of words over the rule, which, rather than banning arbitration clauses altogether, prohibits those agreements from forcing consumers to waive their right to file class action lawsuits. Critics of the rule have said it would effectively do away with arbitration agreements, because companies would not subsidize arbitration programs if they still faced the risk of a class action.

Most recently, Cordray wrote a guest column in The Hill, just days after the news outlet published a piece by Noreika that urged the U.S. Senate to undo the arbitration rule through the Congressional Review Act. While the Senate considers vacating the rule, the CFPB is defending the regulation in Texas federal court against a challenge brought by a coalition of financial industry groups and the U.S. Chamber of Commerce, which are represented by a team from Mayer Brown.

Noreika has raised concerns that the arbitration rule would jeopardize the “safety and soundness” of the financial system, although he declined to push for the Financial Stability Oversight Council to veto the regulation. Referring to the earlier criticism, Cordray described Noreika’s column in The Hill as a “second gratuitous attempt to undermine the evidence that supports our rule.”

“Both times he has relied on so-called analysis that is simply embarrassing,” Cordray wrote.

“We pointed out the far-fetched nature of those claims at the time,” he added. “The total costs of the arbitration rule are pegged at under $1 billion per year, compared to bank profits of $171 billion last year and an asset base of many trillions of dollars. The acting comptroller ultimately stood down and decided not to challenge the rule before the Financial Stability Oversight Council.”