(Reuters) -The U.S. Department of Justice will cease defending the independent status of three consumer and worker protection agencies, according to a letter posted by a Democratic member of Congress on Wednesday.

The determination applies to the National Labor Relations Board, U.S. Federal Trade Commission and Consumer Product Safety Commission, according to the letter from Acting Solicitor General Sarah Harris to Senator Richard Durbin, a Democrat from Illinois and the ranking member of the Senate Judiciary Committee.

Under a 90-year-old Supreme Court precedent, FTC commissioners and members of many other bipartisan independent agencies can only be fired for cause, unlike executive branch agencies whose heads the president can fire at will.

The DOJ will ask the Supreme Court to overturn that ruling to the extent that it protects regulators who wield "substantial executive power" from being fired by the president, Harris wrote, according to the letter.

"I am writing to advise you that the Department of Justice has determined that certain for-cause removal provisions that apply to members of multi-member regulatory commissions are unconstitutional and the Department will no longer defend their constitutionality," Harris said.

The Justice Department did not immediately respond to a request for comment.

Once NLRB board members are confirmed, federal law allows them to be removed only for "neglect of duty or malfeasance in office." CPSC and FTC commissioners have similar protections.

About two dozen companies, including Amazon and Elon Musk's SpaceX, have filed lawsuits since last year claiming the president should have the power to fire NLRB members at will.

Several companies sued by the FTC have filed similar challenges against that agency. They include Meta Platforms, Walmart, and Cigna's Express Scripts.

Trump fired a member of the NLRB and a member of the Merit Systems Protection Board, which hears appeals by federal government employees when they are fired or disciplined, during his first weeks in office. Both have sued over their firings.