Reports: FBI investigating Sen. John Ensign

Politico.com and the watchdog group Citizens for Responsibility and Ethics in Washington both report that the FBI has opened a criminal investigation into Nevada Senator John Ensign's sex scandal and his conduct in handling the situation.

That report comes even as the Senate Ethics Committee is collecting testimony. Senate investigators issued subpoenas last month to former Ensign staffers among others.

Ensign admitted at a press conference in June that he had had an affair with Cindy Hampton, a senior staff member.

Melanie Sloan, executive director of CREW, said reports of the FBI's involvement aren't a surprise, "because there is reason to believe Sen. Ensign was involved in at least two felonies."

Specifically, she referred to allegations Ensign conspired to help former aide Doug Hampton violate the law banning former top aides from lobbying the Senate for a full year after leaving and failing to report a $96,000 gift from Ensigns' parents to Hampton and his wife Cindy - a gift which could violate federal law as well.

"The fact that the FBI is investigaing makes clear that no one - not even a powerful United States Senator - is above the law," Sloan said in a statement. "It is time for him to resign."

Ensign has maintained throughout the scandal that he did nothing illegal and that the investigations into his conduct will prove just that.