WASHINGTON (AP) — Treasury Secretary Steven Mnuchin is urging senators to vote against a Democratic resolution that would maintain sanctions on companies linked to Russian oligarch Oleg Deripaska.

Mnuchin met with Republican senators behind closed doors Tuesday in the hours before a planned Senate vote on the sanctions resolution. The measure would block a Treasury Department move to lift penalties against the aluminum manufacturing giant Rusal and two other companies connected to Deripaska.

Speaking to reporters after the meeting, Mnuchin said, "We have been tougher on Russia with more sanctions than any other administration." He said the sanctions "shouldn't be a political issue."

The Treasury Department says the Russian companies have committed to separating from Deripaska, who will remain blacklisted as part of an array of measures announced in early April that targeted tycoons close to the Kremlin. It also warns that the sanctions could upset global aluminum markets.

The vote comes as Democrats have questioned President Donald Trump's Russian ties and questioned whether his administration is being too soft on Russia. Senate Minority Leader Chuck Schumer, D-N.Y., who introduced the resolution and called for a vote on it, called the Treasury Department decision "sanctions relief for President (Vladimir) Putin's trusted agents." Congress has 30 days to block the move to terminate the sanctions.

Democratic House leaders have also criticized the move and are considering a similar vote. The new Democratic chairmen of seven committees called Mnuchin in for a classified briefing last week on the easing of the sanctions.

At issue is a December announcement from the Treasury Department that the U.S. would lift sanctions on the three companies — Rusal, EN+ Group and the Russian power company JSC EuroSibEnergo. EN+ Group is a holding company that owns nearly 50 percent of Rusal.

In a letter asking Mnuchin for a briefing, the committee chairmen said the sanctions deal appears to allow Deripaska to keep "significant ownership" of one of the companies. They did not elaborate.

The Treasury Department maintains that the companies have committed to diminish Deripaska's ownership and sever his control. In a statement released ahead of the House briefing, Mnuchin reiterated that Deripaska remains under sanctions, "his property and interests remain blocked, and any companies he controls are also sanctioned."

Treasury added that if the companies remained under sanctions, the Russian government might move to nationalize the company, thus shutting it out from any outside control.

Democrats have asked for an extension of the 30-day timeline because the sanctions announcement came just before a holiday recess and the start of the government shutdown. Mnuchin said after his Senate meeting Tuesday that they will see how the Senate vote goes.

"Our view is that we have great responsibility in managing the sanctions programs all over the world, and we take those responsibilities very seriously at Treasury," Mnuchin said.