WASHINGTON (AP) — Four Nuclear Regulatory commissioners from both parties say they have “grave concerns” about the panel’s chairman, charging that the actions of Gregory Jaczko are “causing serious damage” to the commission and creating a “chilled work environment at the NRC.”

In a letter to the White House, the commissioners say Jaczko’s bullying style could adversely affect the agency’s mission to protect health and safety at the nation’s 104 commercial nuclear reactors.

The two-page letter, signed by four of Jaczko’s colleagues on the five-member panel, stops short of calling for the chairman to resign. But it says he “intimidated and bullied” senior career staff, ordered staff to withhold information and ignored the will of the panel’s majority. The letter was signed by Democrats William Magwood and George Apostolakis, as well as Republicans Kristine Svinicki and William Ostendorff.

Jaczko, in a detailed response also sent to the White House, said problems at the agency were not his fault but instead stem from “lack of understanding” on the part of the other four commissioners.

Copies of the letters were obtained by The Associated Press.

The dueling letters come as Jaczko faces hearings in the House and Senate next week in which his behavior is likely to be an issue.

Commission members and staffers have long complained about Jaczko’s brusque style, particularly when it comes to a decision he made last year to shut down the technical review of a proposed nuclear waste dump at Yucca Mountain in Nevada. GOP lawmakers also complained that Jaczko may have acted illegally when he declared in March that Japan’s nuclear crisis constituted an emergency in the United States.

Rep. Darrell Issa, R-Calif., chairman of the House Oversight and Government Reform Committee, said the letter from the four NRC commissioners shows a serious breach in trust among the five-member commission. Issa’s committee is scheduled to hold a hearing on the NRC on Wednesday.

President Barack Obama “has the authority to take action to address these concerns,” Issa wrote in a letter Friday to White House Chief of Staff William Daley. “The public deserves to understand what actions have been taken, and whether the president still believes that Chairman Jaczko is capable of leading the NRC.”

The dispute comes after an inspector general’s report released in June exposed long-simmering internal strife under Jaczko. The agency watchdog said Jaczko intimidated staff members who disagreed with him and withheld information from members of the commission to gain their support.

In August, Republican senators asked the inspector general to investigate whether Jaczko had authority to declare the Japan nuclear crisis an emergency — which grants him additional powers — since the crisis occurred on foreign soil. A Japanese nuclear plant was crippled by a tsunami last March. The senators also said they were not certain that Jaczko has rescinded the order, despite his public claims to the contrary.

In addition to the Oct. 13 letter to Daley, the four NRC commissioners also wrote a letter to Jaczko, saying his “intemperate and disrespectful behavior towards your fellow commission members is completely unacceptable.”

They cited an Oct. 5 meeting with senior staff in which he reportedly expressed “disdain” for commission procedures and “contempt for the commission” itself. The letter called the conduct “absolutely unacceptable.”

Jaczko said in his letter that his “sole and passionate focus” since joining the agency in 2005 has been on nuclear safety and security.

“Unfortunately, all too often, when faced with tough policy calls, a majority of this current commission has taken an approach that is not as protective of public health and safety as I believe is necessary,” Jaczko wrote.

Jaczko denied there is a “chilled work environment around me” and said he never attempted to intimidate anyone.

Jaczko, 41, who is a Democrat, was named to the commission by President George W. Bush and appointed chairman by Obama in May 2009. He said he has a seven-year track record of working collegially and productively with many different commissioners, members of Congress, administration officials from both parties, nuclear plant operators and members of the public.

Earlier this week, Jaczko told reporters he could not think of anything he would have done differently in the past year.

“I come to work every day to do my job better than I did the day before,” he said. “So I am sure there are things I could have done differently.”

He has not had a chance to reflect, Jaczko added, “but I’m the last person to tell you that I’m perfect, and I’m sure there are plenty of things I could have done better.”

Still, Jaczko said he was “very proud of the way this agency responded to a tremendously difficult circumstance” after the crisis in Japan.

Most of the criticism of Jaczko centers on his response to the Japan crisis and his efforts to stop the nuclear waste dump at Yucca Mountain.

Jaczko, a former aide to Senate Majority Leader Harry Reid, the Nevada Democrat who is Yucca’s leading opponent, has made a series of decisions that have aided the Obama administration’s goal of shutting down Yucca Mountain. His purported reasons for doing so have come under attack by Congress, his fellow commissioners and in-house experts as being contrary to the 1982 law that requires the NRC to review the government’s plans for an underground repository in Nevada for the country’s spent nuclear fuel.

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