Sen. Ron Wyden is again pushing the Treasury Department to hand over documents about Russians possibly funneling money to the National Rifle Association.

It’s a renewal of a request the Oregon Democrat first sent to Treasury Secretary Steven Mnuchin at the beginning of February. And now, joined by fellow Democratic Sens. Sheldon Whitehouse of Rhode Island and Robert Menendez of New Jersey, the query is expanding.

Wyden is the ranking Democrat on the Finance Committee, and the other two senators are members of the panel.

“To this date, his office has not received so much as an acknowledgement of the request, let alone a sufficient response,” the senators wrote Monday.

Specifically, the senators want to know of documents related to Russian Central Bank Deputy Gov. Alexander Torshin’s potential contributions to the gun rights lobbying group in connection with 2016 campaign efforts.

The senators suspect that Torshin is an unnamed Russian official who was identified in connection with the arrest of Maria Butina on charges of acting as a Russian foreign agent.

The Democratic senators seek, “production of any documents relevant to financial links between the NRA, its associated entites and Ms. Butina and any entities es or individuals related to her.”

Wyden is a member of the Senate Intelligence Committee, which has continued to investigate Russian interference in the 2016 presidential election, and Butina has testified before the committee as part of that query.

Correction: An earlier version of this story misspelled Maria Butina’s name.