LAS VEGAS — U.S. Sen. John Ensign's decision this week to resign marked a mysterious change of heart for the Nevada Republican, raising questions about what an ongoing Senate ethics probe has uncovered while also muddling the field of candidates for congressional seats now held by the GOP headed into a key election year.
Leaders of the Senate Ethics Committee noted tersely that Ensign made the proper decision in turning in a letter of resignation amid their unfinished two-year probe of his conduct.
Ensign, 53, cited "wear and tear" on himself and his family in his announcement Thursday, which came nearly two years after he acknowledged having had an extramarital affair with a former staffer. The ethics probe has explored Ensign's handling of the affair and whether he tried to illegally cover it up.
As recently as last month, Ensign said he would stay in office because he had not violated ethics rules.
"If I was concerned about that, I would have resigned, because that would make the most sense, because then it goes away," Ensign said when announcing his retirement from politics after 2012.
It's not immediately clear what, if anything, has changed since he made those remarks. An ethics committee official said Friday that neither a vote nor a public hearing had been scheduled in the Ensign investigation prior to his announcement.
Ensign's exit protects him from future disciplinary action and questioning. The committee cannot penalize Ensign once he is no longer a senator, and, with the Senate in recess, it is unlikely that the committee will be able to do so before Ensign's May 3 resignation.
But Ensign is not entirely in the clear. It is likely the committee will move forward on the months-long investigation by issuing an embarrassing statement regarding the propriety of Ensign's behavior and the panel even go so far as to recommend a criminal investigation. It would by a damning, but mostly symbolic, gesture because committee members do not have authority over federal investigators.
Ensign's looming departure also casts a new sense of urgency over Nevada's closely watched Senate race to replace him. After he announced last month that he would not seek re-election, Democrats hoped to claim the seat to protect their fragile Senate majority.
In the meantime, Republican Gov. Brian Sandoval will appoint a successor to serve the remainder of the term through 2012. Sandoval had endorsed Republican Rep. Dean Heller of northern Nevada in the race and is widely expected to name him the incumbent, affording Heller an advantage over Rep. Shelley Berkley, the Democrat's favored candidate.
A Heller appointment to the Senate would require an unprecedented special congressional election in Nevada.
Because of a quirk of Nevada politics, state leaders are uncertain about how to carry out the never-enforced special election law, which does not allow for a primary. Their decision could decide the political fate of tea party favorite and perennial candidate Sharron Angle, who has been running for Heller's seat and could be closed out of the race if party leaders are allowed to pick their general election contestants.
Ensign insisted Thursday he has done nothing wrong. But he said he was shaken by the Senate Ethics Committee decision in February to name a special counsel to look into the matter, after the Justice Department and the Federal Election Commission investigated and then dropped their cases.
"I was hopeful that, with the closure of these investigations against me, the wear and tear on my family and me would soon be over. This was not the case," he said.
Still, the timing of Ensign's announcement remains an enigma given his persistent insistence that he would not give up his seat.
Long after party leaders revoked their support for him, Ensign continued to say he would campaign for a third term until the abrupt announcement in March that he would sit the election out.
Federal campaign reports showed his fundraising efforts had languished. Ensign, however, cited his desire to protect his family from campaign attacks involving the extramarital affair and said the Senate investigation hadn't influenced his decision.
The panel's chairman, Sen. Barbara Boxer, D-Calif., and the vice chairman, Johnny Isakson, R-Georgia, issued a terse statement Thursday saying the committee had spent 22 months investigating "and will complete its work in a timely fashion."
"Senator Ensign has made the appropriate decision," the statement said.
Ensign announced in June 2009 that he had an extramarital affair with Cynthia Hampton, a former member of his campaign staff. Amid the scandal, his parents provided the Hamptons with $96,000, described as a gift, and Ensign helped find Doug Hampton, the husband, a lobbying job.
Doug Hampton has been indicted for illegally lobbying the senator's staff. Federal law prohibits a former senior Senate aide from lobbying the Senate for one year after terminating employment.
Several national and state Republican leaders have said they hope Sandoval will appoint Heller to Ensign's seat.
Sandoval declined to discuss his selection process Friday, but said he would name a successor while Ensign was still in office.
Berkley and Heller had been evenly matched, with their comparable political credentials and name recognition in Nevada. Wealthy businessman Byron Georgiou is also seeking the Democratic nomination.
But choosing Heller or another Republican would give the GOP a clear, albeit slight, advantage of incumbency in a highly competitive seat that could decide which party controls the Senate after next year's elections.
It could also shape the line-up of Nevada's four House contests in a year where President Barack Obama's re-election bid could turn out votes for other Democratic candidates.
State officials don't know how they would proceed in the event of a special election.
"The vacancies that we are talking about don't even exist yet," said Robert Walsh, deputy secretary of state for southern Nevada. "So we are going to use this time to do considerable research in order to have a well-considered legal opinion as to how to proceed."
Election lawyer Burt Odelson, who served on George W. Bush's legal team during the 2000 Florida recount, said primary-free general elections are unheard of or very rare.
"It's going to be a real headache," he said. "They will have to set the precedent and then someone will sue and it will have to be decided in court."
Associated Press writers Sandra Chereb in Carson City and David Espo in Washington, D.C., contributed to this report