Washington (CNN) Treasury Secretary Steven Mnuchin said Wednesday the Trump administration is "actively working" on imposing sanctions on Russia over its interference in the 2016 US election.

"We are actively working on Russia sanctions coming out of the classified briefing," Mnuchin told lawmakers on the Senate Finance Committee, where he was testifying on the President's 2019 budget.

The secretary has come under repeated fire by Democrats for the administration's failure to implement an overwhelmingly bipartisan measure that gives Treasury new authorities to impose sanctions on Russia.

"I can assure you those sanctions are coming," Mnuchin said. "We are working on them as we speak."

The Trump administration didn't levy a single sanction on Jan. 29, the first day it could have under the Countering America's Adversaries Through Sanctions Act. That day, anyone doing business with certain Russian intelligence and military entities, including arms manufacturers, faced possible penalties.

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