Two senior senators are urging President Donald Trump to fully use the new authority to punish Russia that lawmakers overwhelmingly granted him last month.

Sens. John McCain (R-Ariz.) and Ben Cardin (D-Md.) wrote to Trump on the eve of a key deadline in the Russia sanctions bill, which won lopsided bipartisan support in Congress and forced the president to get tougher on Moscow over its election meddling. That legislation requires the administration to identify by Friday individuals linked to Russian defense and intelligence operations who could be subject to new penalties.

McCain and Cardin urged Trump to meet the deadline in a way that “expansively defines these actors to ensure that the perpetrators of the attack on our democracy last year — the defense and intelligence sectors — are sanctioned appropriately.”

“We are very concerned that Russia may attempt to work around sanctions by funneling the arms trade through companies not included in the administration’s guidance,” the senators added.

Beyond that deadline, McCain and Cardin pressed Trump to “fully implement” another section of the sanctions measure that adds new penalties for companies connected to Russian oil and gas projects. They also asked Trump to nudge European allies to coordinate their sanctions in line with the U.S. system, asking for a briefing from the State and Treasury Departments.

And the duo also delivered a broader warning to Trump that lawmakers would take advantage of the popular sanctions bill’s authority to force a congressional review of any decision to ease or end sanctions against Russia.

“As you know, the law provides for Congress to review any administration determination to remove sanctions designations on individuals or entities,” McCain and Cardin wrote. “Based on the overwhelming Congressional support for enacting this law, and that provision in particular, Congress will undoubtedly take that role seriously.”