WASHINGTON -- The Senate ethics committee has begun issuing subpoenas in the scandal surrounding Sen. John Ensign, seeking records on his relationship with former top aide Doug Hampton, sources confirmed Friday.
"They are looking for documents," said one person who reported receiving a subpoena earlier this week from Senate investigators.
Hampton left Ensign's employ as administrative assistant at the end of April 2008, four months after discovering that the Nevada Republican senator was having an affair with his wife. Cindy Hampton, who had been treasurer of Ensign's political committees, left at the same time.
Doug Hampton has alleged that Ensign subsequently tried to cushion his departure by arranging for him to get work as a lobbyist for several Nevada firms, and helped set up a meeting with Transportation Secretary Ray LaHood, in violation of a federal law that requires a one-year "cooling off" period before top Senate aides can lobby.
A spokesman for one of the companies, NV Energy, confirmed it has received a request for information on the subject.
"The Company has received a request for information by the Senate and intends to cooperate in providing such information," NV Energy spokesman Rob Stillwell said in an e-mail.
It isn't known whether another firm, Allegiant Travel Company, has received a similar request. Allegiant CEO Maurice Gallagher was an Ensign contributor and Hampton worked at the company as a government affairs specialist after leaving Ensign's office.
Hampton attorney Daniel Albregts did not respond to a request for comment.
The issuance of subpoenas signals the Senate ethics committee is moving from a preliminary phase into a more substantial investigation of Ensign that could take months to unfold. All the while the probe figures to keep a cloud over the 51-year-old two-term senator, who once was a rising star in Republican circles but now is among the Senate's rank and file.
Hampton, once a close friend, has waged an aggressive crusade against Ensign, portraying the senator as being in relentless pursuit of another man's wife and reckless in trying to finesse the end of his relationship with the couple.
Ensign has admitted a nine-month affair with Cindy Hampton, from December 2007 to August 2008. Otherwise he has denied any unethical or illegal behavior.
An Ensign spokeswoman declined to comment on Friday. In response to Hampton's charge of lobbying wrongdoing, Ensign previously said in a statement: "I am confident we fully complied with the relevant laws and rules governing current and past employees."
Similarly, the Senate ethics committee did not comment on Friday, as is its practice. The committee consists of six senators -- three Democrats and three Republicans -- and is led by Sen. Barbara Boxer, D-Calif.
The committee has broad jurisdiction to investigate allegations of impropriety that reflect on the Senate, and faces no deadlines in pursuing its probes. The investigation could result in committee action ranging from outright dismissal of the matter to a reprimand or a recommendation that the full Senate consider censure or expulsion.
Among Hampton's accusations is that Ensign tried to buy his silence and that of his wife through a $96,000 payment from the senator's parents as the couple was leaving Ensign's employ. The payment was structured for tax purposes and characterized by Ensign's attorney as a gift. Hampton said he has evidence that it was a severance payment, which would have needed to be reported to the Federal Election Commission.
Hampton also has said that Ensign insisted on throwing the couple a going-away party to disguise the purpose of their departures.
The Senate has little choice but to investigate Ensign further, given the charges that Hampton has leveled in high-profile interviews with the New York Times and ABC News Nightline, said Melanie Sloan, executive director of Citizens for Responsibility and Ethics in Washington.
The ethics group filed complaints against Ensign with the Senate, the Justice Department and the Federal Election Commission soon after the scandal came to light in June when Ensign confessed to the extramarital relationship.
Sloan said the ethics committee's call for documents suggests the Justice Department may have "punted" on its own investigation. Customarily, Justice asks the Senate to hold off on its probes if it appears it might complicate an ongoing federal investigation.
"Obviously the Senate Ethics Committee voted to go forward and conduct an investigation," Sloan said. "That seemed, to me, foreseeable. It suggests, perhaps, the Justice Department isn't going forward."
A Justice Department spokeswoman would not comment.
Las Vegas Review-Journal writer Benjamin Spillman contributed to this report.