A group of 21 current and former Democratic lawmakers, including U.S. Sen. Elizabeth Warren and the House and Senate minority leaders, are backing the Consumer Financial Protection Bureau as it fights a court ruling that said the agency's single-director structure is unconstitutional.

The Democrats, represented by Elizabeth Wydra of the Constitutional Accountability Center, want the full U.S. Court of Appeals for the D.C. Circuit to overturn a panel ruling that struck down the CFPB's leadership design. In a proposed friend-of-the court brief filed late Tuesday, the Democrats urged the court to restore the agency's structure.

Writing for the D.C. Circuit panel, Judge Brett Kavanaugh in October lambasted the "massive, unchecked power" afforded to the CFPB director. The agency's leader, Kavanaugh wrote, "enjoys more unilateral authority than any other officer in any of the three branches of the U.S. government, other than the president." The appeals court said the president must have the power to fire the CFPB director at will, rather than only for "inefficiency, neglect of duty, or malfeasance in office."