A pair of influential House Democrats are investigating what they called a “complex web of relationships” between some National Rifle Association bigs and Russians with ties to the Kremlin.

In a letter members said they were sending to NRA chief Wayne LaPierre, a copy of which was shared with ABC News, Reps. Ted Lieu of California and Kathleen Rice of New York voiced concerns that the gun lobbying group was trying to downplay a trip to Moscow by a group of NRA bigs.

The NRA’s outside counsel William Brewer had said earlier that LaPierre opposed the trip and even stopped staff members from going for fear it would be seen as an official visit.

But internal NRA emails and photos on social media reviewed by the network appear to show the organization was neck-deep in the planning of the event.

Lieu, a member of the Judiciary Committee, and Rice, a member of the Homeland Security Committee, suggested the discrepancy might be evidence of an attempted cover-up, and demanded details about communications, meetings and financial transactions between NRA officials and people linked to Russia.

“We are disturbed by the lack of transparency the NRA has demonstrated surrounding the December 2015 trip to Moscow,” wrote Lieu and Rice on Feb. 15. “Furthermore, we are concerned that this extends to other allegations that have been made against the organization as it relates to Russia.”

Citing what they called the NRA’s “unusually close relationship” with the Trump campaign, as well as its record spending on his campaign, Lieu and Rice want to know whether the Kremlin might have used the NRA to funnel foreign money into the 2016 election.

“How much money did the NRA receive from Russia or Russia-linked individuals or entities during the 2016 election cycle?” the lawmakers asked.

“Did the NRA use any of that money in their 2016 election campaign contributions?”

A similar probe is already underway in the Senate, but the Democrats hold the majority in the House, meaning their requests for documents or interviews can be compelled by subpoena — an authority controlled by the party in power.

Brewer did not immediately respond to a request from ABC for comment.