Washington ? Republican Sen. Pat Roberts of Kansas is preparing to leave the Senate Intelligence Committee after an intense four years as chairman, according to Senate officials.

Roberts has been a lightning rod for partisan criticism throughout his tenure, which began just weeks before the United States invaded Iraq in March 2003.

The Intelligence Committee, once noted for bipartisan collegiality, increasingly was swept into the maelstrom of vitriol surrounding the intelligence that led to the Iraq war, the Bush administration’s domestic surveillance program and the treatment of suspected terrorists in custody.

Neither Roberts nor his spokeswoman would comment for this story.

Critics say Roberts did the bidding of the Bush administration and dragged his feet on oversight, especially the investigations of prewar intelligence leading to the Iraq invasion. A year ago, Democrats briefly forced a shutdown of the Senate to protest Roberts’ stewardship of the investigations. Committee Vice Chairman Jay Rockefeller, D-W.Va., once accused Roberts of taking “all his talking points from the White House.”

Roberts’ defenders say he provided appropriate, forward-looking oversight and tried to avoid airing dirty laundry that could have compromised national security. Republican committee member Christopher Bond of Missouri applauded Roberts for “working hard on a bipartisan basis to try to move forward.”

“Reasonable people can disagree about whether he did a really good job or whether he saved the president’s hide,” said John Pike, the director of Globalsecurity.org, a nonpartisan defense research center. “But it was an unusually tough assignment. How do you balance the intelligence community’s obsession with secrecy with a public that has a difficult time understanding why no one stopped Sept. 11 and why the intelligence on Iraq was so at odds with reality?”

Sen. Carl Levin, D-Mich., left, and Senate Intelligence Committee Chairman Sen. Pat Roberts, R-Kan., talk before an April 12, 2005, hearing on John Negroponte's nomination to be Director of National Intelligence. Roberts is preparing to leave his spot as chairman of the Intelligence Committee, Senate officials say.

Among Roberts’ accomplishments: issuing a unanimous committee report in July 2004 that found intelligence leading to up to the war was faulty, overseeing a massive reorganization of the U.S. intelligence community and persuading the White House to brief the entire committee on the domestic surveillance program, rather than just the chairman and vice chairman.

The committee has released two of its five so-called “Phase II” investigations that delve more deeply into issues regarding prewar intelligence on Iraq. Still to come is the most potentially explosive: Comparing the prewar statements of government officials with the intelligence available at the time.

The Senate officials, speaking on condition of anonymity because Senate committee assignments still are being worked out, said Roberts was weary of the carping associated with the committee’s work and was concerned that partisanship might increase as Democrats lead the committee in the final years of the Bush administration. Roberts has been on the committee since his arrival in the Senate in 1997.

Roberts, 70, plans to run for re-election in 2008. He had no major party opposition in 2002, but since then the Democratic Party has had a resurgence in Kansas. Taking a different committee assignment would allow him to do more work directly related to Kansas and become less associated in the public mind with the increasingly unpopular Iraq war, the officials noted.

It’s unclear who would replace Roberts as the top Republican on the Intelligence Committee. Sen. Orrin Hatch of Utah is next in line, but one official said Hatch may prefer to become ranking Republican on another committee. Hatch’s office would not comment.

That would leave the job open to Bond, who has taken an increasingly prominent – and frequently partisan – role in intelligence matters during the last two years. Bond, who often served as GOP sound-bite bad cop to Roberts’ more reserved good cop, also is writing a book on terrorism in Southeast Asia. Bond said that as far as he knew, Roberts would remain top Republican on the committee.