Senator Ensign to Resign Amid Inquiry

Washington – Senator John Ensign of Nevada, the subject of an ethics investigation related to his affair with the wife of a former top aide, announced Thursday evening that he was resigning, effectively ending the high-profile Senate inquiry that had already ruined his once-promising political career.

“It is with tremendous sadness that I officially hand over the Senate seat that I have held for eleven years,” Mr. Ensign, a Republican, said in a statement. “The turbulence of these last few years is greatly surpassed by the incredible privilege that I feel to have been entrusted to serve the people of Nevada.”

Mr. Ensign acknowledged that his departure was inspired in part to avoid formal charges of wrongdoing.

“While I stand behind my firm belief that I have not violated any law, rule, or standard of conduct of the Senate,” he said, “and I have fought to prove this publicly, I will not continue to subject my family, my constituents, or the Senate to any further rounds of investigation, depositions, drawn out proceedings, or especially public hearings. For my family and me, this continued personal cost is simply too great.”

The Democrat and Republican who lead the Senate Ethics Committee released a two-sentence statement late Thursday, hinting that the investigation had documented wrongdoing that merited Mr. Ensign’s departure.

“The Senate Ethics Committee has worked diligently for 22 months on this matter and will complete its work in a timely fashion,” said the statement by Senator Barbara Boxer, Democrat of California, and Senator Johnny Isakson, Republican of Georgia. “Senator Ensign has made the appropriate decision.”

Mr. Ensign’s resignation, which will take effect May 3, will allow Nevada’s governor, Brian Sandoval, to appoint a Republican to fill out the rest of the Senate term, thereby increasing the chances that the party would hold on to what may be a hotly contested seat next year. One likely candidate is Representative Dean Heller, a Republican House member already running for the job. Mr. Ensign had not been planning to run for re-election.

If Mr. Heller is appointed, he will be able to run as an incumbent, and by leaving the House he could also avoid some of the politically charged votes expected to occur there in the coming months.

One Democratic member of Congress, Representative Shelley Berkley, is already running for the seat.

The resignation marks the final chapter in the career of a politician who a few even thought might reach the White House, but who instead got caught up in a particularly salacious Washington scandal. Mr. Ensign, 53, a veterinarian and former casino executive, had cast himself as a religious conservative, and lived with other lawmakers in a Capitol Hill townhouse run by a religious group.

But in 2007 he began an affair with the wife of Doug Hampton, his best friend. The families had been close, vacationing together once. Their children were playmates, and the senator even encouraged Mr. Hampton to come to Washington, where Mr. Hampton became his most loyal aide. Mr. Hampton’s wife, Cynthia, worked as treasurer of Mr. Ensign’s campaign and political action committee.

After learning of the affair in 2008, Mr. Hampton confronted the senator. Soon after, he and his family were given $96,000 by the senator’s parents, described by Mr. Ensign as a gift, and Mr. Hampton left the senator’s staff.

Senate ethics investigators have been examining whether that payment may in fact have been an illegal campaign contribution by Mr. Ensign’s parents as part of an effort to buy Mr. Hampton’s silence. In a series of interviews with The New York Times in 2009, Mr. Hampton also said the senator had helped him get started in his new career as a lobbyist, pushing prominent Nevada executives to hire him, with the understanding that Mr. Hampton would be able to influence Mr. Ensign.

The final step in the Senate ethics investigation before a public statement about possible formal charges against Mr. Ensign would have been a sworn deposition by the senator himself. It is unclear whether that has occurred.

Mr. Ensign, a former chairman of the National Republican Senatorial Committee, has acknowledged that he helped Mr. Hampton get lobbying work, and that he then took official actions to help Mr. Hampton’s clients, an airline and an electric utility. But he said he had not taken those steps at the request of Mr. Hampton, but because they were constituents.

The ethics committee still has the power to issue a public statement outlining the results of its investigation. One Senate official said that given a year and a half of work looking into the matter — and the public interest in its outcome — that the step was likely. It also has the power to make a referral to the Justice Department, which has been conducting its own inquiry, urging it to consider possible criminal charges.

The ethics investigation, which had included the appointment of an experienced former federal prosecutor as an outside special counsel, was considered by Senate officials to be the deepest examination of possible wrongdoing since the ethics committee in 1995 recommended that Senator Bob Packwood, a Republican from Oregon, be expelled. He resigned instead, after accusations of sexual harassment by former members of his staff.

Robert L. Walker, Mr. Ensign’s lawyer, declined to comment Thursday.

The senator’s lawyers said late last year that they had been informed by the Justice Department that it had concluded its investigation. But Justice Department officials would not confirm that such a step was taken.

So far, Mr. Hampton is the only individual to be charged formally with any wrongdoing, as last month, the Justice Department filed criminal charges accusing him of lobbying Mr. Ensign’s office in 2009, after he left his Senate job, despite a one-year lobbying ban. He has pleaded not guilty.

On Thursday, Mr. Ensign’s fellow Nevada senator, Majority Leader Harry Reid, said, “I know this is a difficult time for the family and I wish them all well as they work through it.”

Carl Hulse contributed reporting.

This story “Senator Ensign to Resign Amid Inquiry” originally appeared in The New York Times.