The Federal Election Commission has opened a preliminary investigation in whether the National Rifle Association took illegal contributions from Russian organizations that were meant to benefit Donald Trump’s 2016 presidential campaign, according to Politico. The investigation is partly a result of a complaint from American Democracy Legal Fund, a progressive advocacy group that filed a complaint requesting the FEC look into reports of ties between Russians and the NRA.

The liberal group cited reports that a Russian banker with ties to the Kremlin may have tried to influence the elections by donating money to the gun-rights advocacy organization. Reports in January claimed that the FBI was looking into allegations that the banker, Alexander Torshin, donated money to the NRA as a way to boost Trump’s campaign.

Sen. Ron Wyden, a Democrat from Oregon who is the ranking member of the Senate Finance Committee, is also investigating possible collusion between Russia, the NRA, and Trump’s campaign. “I am specifically troubled by the possibility that Russian-backed shell companies or intermediaries may have circumvented laws designed to prohibit foreign meddling in our elections by abusing the rules governing … tax exempt organizations,” Wyden wrote in a letter to the NRA on Feb. 2.

Although the FEC is not confirming the investigation, the treasurer of the American Democracy Legal Fund said he received confirmation that the preliminary investigation had been launched. If the investigators find compelling evidence to suggest wrongdoing the FEC could possibly refer any findings to Special Counsel Robert Mueller.