WASHINGTON: Gregory Jaczko, chairman of the US Nuclear Regulatory Commission, said on Monday he would resign, after a year of intense criticism of his abrasive management tactics.

Jaczko, 41, was a polarizing figure who oversaw the nuclear safety agency as it crafted expensive new rules in the wake of the 2011 earthquake and tsunami that devastated Japan's Fukushima Daiichi nuclear complex.

But Jaczko made more headlines from a series of reports and congressional hearings that painted him as a bully who had reduced some senior female employees to tears -- accusations he consistently dismissed and denied.

Jaczko, appointed to the chairman role by President Barack Obama, did not say what led to the timing of his announcement.

“After an incredibly productive three years as chairman, I have decided this is the appropriate time to continue my efforts to ensure public safety in a different forum,” Jaczko, a Democrat, said in a statement, noting he will serve until the Senate confirms his successor.

The four other commissioners at the NRC -- two Democrats and two Republicans -- took the unprecedented step last year of complaining to the White House about Jaczko.

Afterwards, Bill Daley, then White House chief of staff, expressed his support for Jaczko and urged the commissioners to get along, perhaps with help from a mediator.

The White House plans to nominate a new chairman soon, a spokesman said in a statement.

The nuclear agency is implementing an extensive overhaul of safety rules for the nation's 104 nuclear plants, owned by companies such as Exelon and Entergy Corp.

It also recently approved licenses for the first new US plants in more than 30 years, owned by Southern Co and Scana Corp. Jaczko cast the lone dissenting vote against the new licenses.

Jaczko, who has spent almost eight years on the commission, had sought to move quickly on the new rules, regularly clashing with the four other commissioners who lead the agency and who favored a more cautious approach.

His departure is a loss for the NRC, said Edward Markey, a Democratic congressman, frequent critic of the nuclear power industry and former employer of Jaczko.

“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,” Markey said in a statement.

The inner turmoil at the NRC first attracted public scrutiny a year ago, when the agency's inspector general, an internal watchdog, released a report that described Jaczko as losing his temper and using threats and intimidation to try to get his way.

A second report on Jaczko from the inspector general is expected to be released imminently.

“Given the numerous reports of Chairman Jaczko's failed leadership at the NRC, it was right of him to step down today,” said Senator James Inhofe, the top Republican on the Senate Environment and Public Works Committee.