Updated: 12:27 p.m.

The controversial chairman of the Nuclear Regulatory Commission resigned Monday morning — but with an important caveat.

Gregory Jaczko, a former aide to Senate Majority Leader Harry Reid (D-Nev.) and opponent of using the Yucca Mountain nuclear waste repository in Nevada, announced he would resign Monday morning but made his resignation effective once the Senate confirms a successor. That will complicate efforts by the nuclear industry and Republicans to replace him with someone friendlier to the industry.

“My responsibility and commitment to safety will continue to be my paramount priority after I leave the Commission and until my successor is confirmed,” Jaczko wrote, adding, “This is the right time to pass along the public safety torch to a new chairman who will keep a strong focus on carrying out the vital mission of the Nuclear Regulatory Commission.”

Reid issued a statement thanking Jaczko.

“He dedicated his tenure to improving the safety of nuclear energy, and his leadership during the Fukushima nuclear crisis protected millions of Americans,” Reid said. “His work toward a safe and effective nuclear energy policy has left Nevada and the nation more secure. 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 pulled out all the stops to get Jaczko appointed to the NRC during the Bush administration, applying blanket holds to the administration’s nominees until they agreed to appoint him.

The other four members of the NRC — two Republicans and two Democrats — complained last year that Jaczko has an abusive and bullying management style.

But Jaczko ignored those attacks in his statement.

“The Nuclear Regulatory Commission was one of the best places to work in the federal government throughout my tenure,” he said in his statement.

The White House said the president would quickly nominate a successor.

“The president appreciates Chairman Jaczko’s service and efforts to further the mission of the Nuclear Regulatory Commission — to license and regulate the nation’s use of nuclear materials,” said White House spokesman Clark Stevens. “A strong and effective NRC is crucial to protecting public health and safety, promoting defense and security and protecting the environment, and we intend to nominate a new chairman soon.”

Senate Minority Leader Mitch McConnell (R-Ky.) sharply criticized the administration for standing by Jaczko to this point.

“Dr. Jaczko’s troubling behavior as chairman of the Nuclear Regulatory Commission had clearly resulted in a hostile work environment for women that ran counter to acceptable norms of workplace equality and that threatened to undermine the mission of the NRC itself,” McConnell said in a statement. “The only thing surprising about his resignation is the fact that the Obama administration has remained silent for more than a year after allegations of Jaczko’s offensive behavior surfaced. Even Democrat commissioners said that Jaczko bullied employees and intimidated female workers as chairman of the commission.”

McConnell urged the White House to replace Jaczko, and he reiterated his call for the Senate to reconfirm Kristine Svinicki for another NRC term before her post expires June 30.

Reid has opposed Svinicki as too close to the industry, but Republicans have accused him of holding up her nomination because she and the other commissioners called out Jaczko last year.