Ensign's parents reportedly paid $96,000 to the family of the former campaign aide with whom he has admitted to having an affair. And he reportedly set up the woman's husband, Doug Hampton, as a lobbyist and directed his staff to maintain contact with Hampton -- a potential violation of lobbying rules, since Hampton had been a top aide to Ensign.
Sources said recently that federal investigators have begun interviewing witnesses in connection to the matter. Ensign has denied breaking any laws.
Politico adds that according to the filings, Ensign has barely started raising money for a possible 2012 reelection bid. He has not said whether he plans to run again.