WASHINGTON (AP) — A federal grand jury has issued subpoenas to a Republican campaign committee and companies in Nevada in a probe of Sen. John Ensign, who has been under scrutiny for his efforts to find lobbying work for the husband of his former mistress.

One subpoena went to the National Republican Senatorial Committee, which was formerly chaired by Ensign, a Nevada Republican, committee spokesman Brian Walsh said Thursday.

Sean Cairncross, general counsel for the group that is the campaign committee for Republican Senate candidates, said the committee has responded appropriately to questions concerning matters related to the time frame of the 2008 election campaign.

On Thursday, a Las Vegas television station reported that grand jury subpoenas in the Ensign probe went to six Las Vegas businesses that it did not name.

According to one subpoena obtained by KLAS-TV, a recipient was ordered to produce documents relating to, among others, Ensign; political consultant Michael Slanker, the former political director at the National Republican Senatorial Committee; and Slanker’s wife, Lindsey, the committee’s former finance director. They worked at the committee when Ensign ran it.

On his Web site, Slanker says his tenure at the committee included oversight and design of the political, communications and research departments. He oversaw and worked day-to-day with more than 20 targeted Senate campaigns.

The subpoena covers the period starting Jan. 1, 2008, and directs the recipient to testify March 31 in Washington, D.C., and to turn over documents. The station posted one subpoena on its Web site with the recipient’s identity blacked out.

Ensign’s affair and the legal problems it has engendered have derailed talk that he might make a run for the Republican presidential nomination in 2012 and forced him to resign his position as chairman of the Senate Republican Policy Committee.

Asked about the subpoenas, Ensign spokeswoman Rebecca Fisher said, “Sen. Ensign is confident he has complied with all ethics rules and laws and will cooperate with any official inquiries.”

The FBI and Senate Ethics Committee are investigating whether Ensign tried to limit political damage from an affair he had with the wife of one of his Senate aides by conspiring to help the aide find a new job as a lobbyist, which might have violated restrictions on lobbying by former congressional staff.

Federal criminal law prohibits congressional aides from lobbying their ex-bosses or office colleagues for one year after departing their Hill jobs.

Ensign acknowledged the relationship with Cynthia Hampton last June. Ensign helped her husband, Doug Hampton, gain employment with a lobbying firm, and Ensign’s parents provided the Hamptons with a payment of $96,000 that they described as a gift.

The affair ended in 2008; Ensign is married.

In Las Vegas, executives of three companies told The Associated Press they had received subpoenas regarding Ensign in recent weeks from a federal grand jury, the Senate Ethics Committee or both.

GOP strategist and longtime Las Vegas businessman Sig Rogich said he provided material both to federal prosecutors and the Senate Ethics Committee about meeting with Hampton after getting a call from Ensign asking him to do so. Rogich said he did not give Hampton a job. Other Las Vegas firms that received subpoenas included The Selling Source LLC and eCommLink.

eCommLink, like a number of other Nevada companies, “has received subpoenas regarding the federal investigation of Sen. John Ensign,” the firm’s chief executive, Ennio Ponzetto, said in a statement.

Glenn McKay, president of The Selling Source LLC, told the AP a subpoena sought records and e-mails about a meeting regarding a campaign contribution between Ensign and Selling Source founder Derek LaFavor. The meeting took place in February or March of 2008, McKay said, adding that no contribution was given and that Hampton’s name did not come up.

Hampton told The New York Times last year that, in coordination with the senator and his staff, he played a significant role in pushing the Washington agendas of NV Energy, the largest power company in Nevada, and Allegiant Air, a Las Vegas-based discount airline. On Thursday, Allegiant Air declined to comment. In a statement, NV Energy said that “as we have said all along, we will cooperate with any federal review.”

The subpoena posted on the TV station’s Web site also seeks documents relating to former Ensign chief of staff John Lopez and the Hamptons.

The subpoena also seeks records regarding November Inc., a political consulting firm belonging to Michael Slanker.

John Lopez, Ensign’s former chief of staff, told The New York Times last year that when he raised concerns about contacts between Hampton and the senator’s office, he was designated as an intermediary to ensure those contacts complied with the law.

Lopez acknowledged that Hampton tried to lobby him, but he said that was Hampton’s problem. Robert Kelner, Lopez’s attorney, declined to comment Thursday about whether Lopez has received a subpoena in the case.

Michael Slanker and officials at November Inc. did not respond Thursday to messages seeking comment. Daniel Albregts, a Las Vegas lawyer representing the Hamptons, declined to comment.

———

Ritter reported from Las Vegas. Associated Press writers Kevin Freking and Liz Sidoti in Washington contributed to this report.