(Reuters) -A federal employees' union on Sunday asked a federal judge to order the Trump administration to fund the top U.S. consumer watchdog, weeks after the agency said its cash could run out by year's end.

In a court filing, lawyers for the National Treasury Employees Union and other plaintiffs disputed officials' claim that they cannot legally fund the Consumer Financial Protection Bureau.

President Donald Trump has sought to dismantle the CFPB since he took office in January and installed Russell Vought, his budget director, as the acting head of the agency. While Vought's effort to fire the vast majority of its employees is tied up in litigation, he has successfully shut down most of the CFPB's activities.

Unlike most federal agencies that receive funding from congressional appropriations, the CFPB draws its funding from the Federal Reserve, a structure intended to give it more independence from political budget battles.

Earlier this month, the bureau under Vought's leadership told the court it could not request more money from the Fed because the law that authorized it specified the funds must come from the central bank's "combined earnings." Since the Fed has been operating at a loss, the filing argued, there are no earnings available.

In Sunday's motion, the union said that interpretation "cannot be squared with the text, purpose, or history of the statute" and accused the government of attempting to sidestep a previous injunction barring the total elimination of the CFPB.

The U.S. Supreme Court last year found the bureau's funding structure constitutional.