Nuclear Regulatory Commission Chairman Gregory Jaczko waits for the beginning of a joint hearing before the Senate Environment and Public Works Committee and Clean Air and Nuclear Safety on Capitol Hill. (Alex Wong/Getty Images)

The nation’s chief of nuclear safety announced his resignation Monday after a three-year tenure marked by debates over regulatory guidelines, praise for the U.S. response to the Japanese nuclear disaster and complaints that he had verbally abused women in the workplace.

The departure of Gregory B. Jaczko, an advocate of tough safety standards at nuclear reactor sites during eight years on the Nuclear Regulatory Commission, caps almost a year of concerns about his leadership of the NRC, which he has chaired since 2009.

Though frequently at odds with fellow NRC commissioners over the extent of safety requirements, it was political timing and management style that ultimately prompted his departure.

The NRC’s inspector general has briefed congressional aides on the contents of a report, due out in less than a month, about allegations that Jaczko treated female staffers harshly, according to people familiar with the briefing who spoke on the condition of anonymity to preserve their business relationships. A draft of the report quoted female staffers saying that his comments made them cry.

In an interview Monday, Jaczko said that the inspector general’s report “had absolutely no role” in his decision and that “any allegations about me targeting women are simply untrue.” He said that with his term expiring in June of next year he “wanted to give the president and Senate the opportunity to go through the process of identifying a candidate. Sometimes these decisions are a gut feeling.”

But in an election year, congressional aides said Jaczko was facing wavering support from his former boss, Senate Majority Leader Harry M. Reid (D-Nev.), who fiercely opposes efforts to store nuclear waste at Nevada’s Yucca Mountain, a key concern of the nuclear agency. In a statement Monday, Reid thanked Jaczko for his service, noting his leadership of the agency in the aftermath of last year’s Japanese tsunami and partial meltdown at the Fukushima nuclear plant.

“I am confident whomever replaces Chairman Jaczko will share his commitment to protecting the safety of the American people over the interests of a single industry,” Reid said.

Jaczko is a former staffer for Reid and other Democratic lawmakers.

The White House can now nominate a replacement who could be paired with Kristine L. Svinicki, a Republican NRC commissioner who requires confirmation for a new five-year term. An industry source, who asked for anonymity to preserve relationships in Congress, said that to replace Jaczko, the White House was considering one of two women with academic backgrounds in nuclear matters, one of whom also has federal government experience.

The choice of a woman to lead the agency would undercut Senate Minority Leader Mitch McConnell’s (R-Ky.) attempt to turn the NRC into a women’s issue by arguing that the White House had unfairly delayed Svinicki’s renomination while standing by Jaczko.

Some Jaczko supporters said he also fell victim to the nuclear power industry and its allies in Congress who seized upon a reason to question his leadership. A voice for tighter safety standards, Jaczko frequently found himself as the sole dissenter in key commission votes.

Jaczko’s tenure as chairman also included the awarding of the first new nuclear construction permit in three decades and the agency’s response to the Japanese tsunami. Earlier, as a commissioner, Jaczko led efforts after the Sept. 11, 2001, terrorist attacks to ensure that new designs strengthen reactors against aircraft attacks.

“This is the right time to pass along the public safety torch to a new chairman,” Jaczko said.

In a statement, Rep. Edward J. Markey (D-Mass.) said, “Greg has led a Sisyphean fight against some of the nuclear industry’s most entrenched opponents of strong, lasting safety regulations, often serving as the lone vote in support of much-needed safety upgrades recommended by the Commission’s safety staff.”

Nuclear Energy Institute President Marvin Fertel said in a statement: “We have had significant differences with the chairman on how best to achieve our mutually shared goals. But to his credit we’ve always had open lines of communications and a willingness to respectfully discuss the issues. This has especially been the case over the past 13 months since the accident at the Fukushima plant in Japan.”

Jaczko had become a target for congressional Republicans.

House Oversight and Government Reform Committee Chairman Darrell Issa (R-Calif.) issued a statement saying that Jaczko’s resignation “will close an ugly chapter.” He added, “This was never about nuclear safety, but rather poor leadership that created an abusive and hostile work environment.”

Much of the concern with Jaczko’s tenure burst into the open in December at a congressional hearing arranged to address whistleblower allegations that he had screamed at female staffers.

“I’m a very passionate and intense and demanding individual and I hold my staff accountable, and if that was misinterpreted by anybody I want to address that,” Jaczko said Monday.

GOP lawmakers had pressed the White House for details on meetings the NRC’s four other commissioners held with then-White House Chief of Staff William Daley to convey concerns.

At the December hearing of the House oversight panel, those commissioners — two Democrats and two Republicans — said they doubted Jaczko’s ability to lead the agency.

Commissioner William D. Magwood, a Democratic appointee, told lawmakers at the hearing that Jaczko regularly grew impatient at meetings with career agency staffers. Magwood said that during one encounter, Jaczko “became increasingly irrational, and everyone in the meeting became very uncomfortable.”

Svinicki told lawmakers that her fellow commissioners “have been on the receiving end of this conduct.”

One battle between Jaczko and his fellow commissioners concerned his recommendation to impose a 50-mile exclusion zone around the troubled Japanese nuclear plant. Other commissioners believed that was too much. However, e-mails released later showed that Jaczko had NRC staff support; later radiation measurements justified the 50-mile zone.

Seated at a witness table with two commissioners on either side, Jaczko insisted during the December congressional hearing that he had done nothing wrong and that he had no plans to resign. He also denied knowledge of incidents in which he was alleged to have verbally abused staffers.

After the congressional hearing, Republicans pressed Jaczko to clarify his testimony, citing conflicting witness testimony gathered by the NRC’s inspector general. Jaczko said Monday that he still plans to reply.