"We strongly urge the agency to only pursue consensus and administrative matters that are non-partisan for the remainder of your tenure," House Energy and Commerce Committee Chairman Frank Pallone wrote in letters to the two agencies joined by the subcommittee chairs overseeing the agencies, Representatives Jan Schakowsky and Mike Doyle.

The FTC held a meeting last month to discuss a pending antitrust investigation into Facebook Inc, but the commission has not decided yet whether to file a complaint, a person briefed on the matter told Reuters at the time. It is not clear what impact the letter may have on the probe.

Pai said last month he would move forward to set new rules to clarify the meaning of a key legal protection for social media companies after a demand by President Donald Trump and over the strong objections of Democrats on the panel.

Trump lost his bid for re-election as media outlets declared former Vice President Joe Biden, a Democrat, the winner.

Representatives for Pai and Simons did not immediately comment.

The two Democrats on the five-member FCC called on Pai to abide by the letter.

"I urge FCC Chairman Ajit Pai to follow this past practice in order to ensure an orderly transition of agency affairs," FCC Commissioner Jessica Rosenworcel said. "I look forward to continuing to work on the routine and consensus matters currently before the agency."

Fellow Democratic FCC Commissioner Geoffrey Starks agreed. "Our congressional leaders have called for Chairman Pai to respect this precedent, and I expect that he will abide by their request," Starks said.

On Jan. 17, 2017, three days before Trump was inaugurated, the two Democrats on the FTC voted to sue chipmaker Qualcomm Inc, accusing it of breaking antitrust law. Republican Maureen Ohlhausen voted against the measure. The other two seats were empty. In September, the FTC filed a motion to rehear the lawsuit it lost on appeal against Qualcomm.

(Reporting by David Shepardson and Diane Bartz; Editing by Chris Reese and Jonathan Oatis)

By David Shepardson and Diane Bartz