WASHINGTON (CNN) -- Steven Kappes and Michael J. Sulick, the top leaders of the CIA's directorate of operations, resigned Monday morning, sources told CNN.

Their departures come in a period of turmoil at the intelligence agency as the new director, Porter Goss seeks to impose his control.

The directorate of operations is the agency's clandestine service.

Kappes took over from James Pavitt, who left in August.

Deputy Director John McLaughlin, who ran the agency after Director George Tenet resigned earlier this year, announced his retirement Friday. He said he was leaving for personal reasons.

Michael Scheuer, the former head of the CIA's search for al Qaeda leader Osama bin Laden, quit Thursday.

In August, President Bush tapped Goss, a former CIA officer and chairman of the House Intelligence Committee, to lead the agency. During his confirmation hearings, Goss pledged to apply "tough love" to the CIA.

Sources say Kappes and Sulick clashed with deputies Goss brought in from Capitol Hill, where he served as chairman of the House Intelligence Committee before being chosen by President Bush as director of central intelligence.

Top Republican lawmakers voiced support for new CIA Director Porter Goss on Sunday after the resignations of McLaughlin and Scheuer raised questions about a possible upheaval in the agency.

Senate Majority Leader Bill Frist said such turnover was to be expected as new leadership takes over.

"The aggressiveness with which we will continue to fight the war on terror for freedom and liberty and democracy throughout the world will not be affected in any way by any sort of personnel changes here or any sort of reorganization of the intelligence functions of entities here," said Frist, a Republican from Tennessee.

But critics suggest Goss may be doing more harm than good with his efforts to reshape the nation's flagship spy agency. California Rep. Jane Harman, the ranking Democrat on the House Intelligence Committee, accused Goss of bringing a "highly partisan, inexperienced staff" with him when he took office in September.

"The agency seems in free-fall in Washington, and that is a very, very bad omen in the middle of a war," Harman said.

Harman said Goss has the right to make changes at the spy agency, but he needs "a management team in place that can help achieve objectives."

"To make those changes effectively, he has to do them with an experienced staff, and he doesn't have one," Harman said. "Many of us worked with that staff in the House. Frankly, on both sides of the aisle in our committee, we were happy to see them go."

Sen. John McCain, an Arizona Republican, called the CIA "a dysfunctional agency, and in some ways a rogue agency" that needed to be reformed. He accused some CIA insiders of leaking information to damage President Bush politically in the months before the election.

"Porter Goss is on the right track," McCain said on ABC's "This Week." "He is being savaged by these people that want the status quo, and the status quo is not satisfactory."

The CIA "is not providing the intelligence information necessary for the president to conduct the war on terror," he said.

Sen. Lindsey Graham, a South Carolina Republican, said the CIA "failed this country" with incorrect assessments of Iraq's weapons programs before the U.S.-led invasion in March 2003.

"I'm not worried about hurting people's feelings," said Graham, a member of the Senate Armed Services Committee. "I want to stand behind those who work hard. But if you got it wrong, you need to be dealt with."

Elaine Quijano contributed to this report.

Commentary: