WASHINGTON — Senate Democrats Wednesday asked the IRS to investigate the National Rifle Association and determine whether the organization should be stripped of its tax-exempt status following a months-long investigation that found that the NRA worked closely with Russian nationals who wanted access to the American political system.

The letter to IRS Commissioner Charles Rettig, written by Sen. Ron Wyden, D-Ore., the ranking member of the Senate Finance Committee and Senate Democratic Leader Chuck Schumer, claims that the NRA didn’t act as a social welfare organization in the run-up to the 2016 elections and violated the restrictions placed on non-profits from profiting off its activities.

“In light of the continued efforts of Russia to undermine American Democracy, IRS must use its full authority to prevent foreign adversaries from again exploiting tax-exempt organizations to undermine American interests,” the senators wrote. “It is incumbent on the IRS to fully investigate the organization’s activities to determine whether the NRA’s tax exemption should be disallowed.”

The investigation, conducted by Senate Finance Committee Democrats who released a report on their findings Friday, found that top officials at the NRA used the organization’s financial resources — largely collected by member dues — to curry favor with two Russians, Aleksander Torshin, the deputy governor of the Central Bank of Russia, and his deputy, Maria Butina, who said they had access to top Russian officials.

The probe was limited in scope and relied on the NRA to voluntarily hand over documents. Republicans on the Finance Committee opted not to cooperate with the investigation.

The staff for Senate Finance Committee Chairman Charles Grassley, R-Iowa, reviewed the documents obtained by Wyden’s staff and issued a separate report stating they found that the $6,000 in question to pay for the trip to Russia is “relatively insubstantial” and the evidence “does not raise concerns that the NRA abused its tax-exempt status purposes” when NRA officials traveled to Moscow in 2015.

“This report goes to great lengths to try to involve the NRA in activities of private individuals and create the false impression that the NRA did not act appropriately. Nothing could be further from the truth,” William A. Brewer III, counsel to the NRA, said about the Democrats’ report.