The Republican staff director of the Senate Select Committee on Intelligence said yesterday that the next phase of the panel's probe of prewar intelligence on Iraq could continue for weeks, after key Democrats on the committee complained there is still much investigative work to be done.

On Tuesday, a bipartisan group of senators plans to meet and launch what the panel has labeled "Phase Two" of its investigation. That phase will focus in part on how the Bush administration handled prewar intelligence, including whether the information was misrepresented in statements to the public. The group of six senators is to meet over three days and report back on the intelligence committee's plan for this second phase.

The meeting was scheduled after Senate Democrats surprised Republican colleagues on Tuesday by invoking a little-used parliamentary maneuver to force the chamber into a rare closed session. Angry Republicans called it a destructive publicity stunt. Democrats said they did it to force Republicans to move ahead with the long-promised Phase Two probe.

Yesterday, Democrats held a news conference to emphasize their position that the inquiry will require time and careful attention. They warned Republicans against trying to rush through the most controversial portion of the review: the comparison of the public statements made by administration and congressional officials about the prewar intelligence known at the time.

"This is serious professional work that needs to be done promptly," said Sen. John D. Rockefeller IV (D-W.Va.), vice chairman of the committee. "And it cannot become a matter of short order -- you know, hamburger."

Sen. Carl M. Levin (Mich.) said he and other Democrats are insisting on assessing whether administration statements "were substantiated by intelligence information," and that it takes time "to see whether or not a particular statement is substantiated."

Among other things, Democrats said they do not believe they have all the intelligence the White House had when it made its statements. Sen. Dianne Feinstein (D-Calif.) noted that "a number of the documents and interviews we need to do the work have been refused by the administration."

The panel's chairman, Sen. Pat Roberts (R-Kan.), issued a statement saying that he is "ready to roll up his sleeves and get going" and that "the real test for the minority will be for them to show up on Tuesday, ready to do the important national security work that has been asked of them."

William Dunke, the intelligence panel's chief of staff, said the committee has prepared by collecting public statements of President Bush and other administration officials, as well as the intelligence data "available at the time." It will be up to the senators to determine in each case if a public statement by Bush or others was justified by the data, he said.

Dunke noted that Phase One of the committee's Iraq investigation -- which focused on the quality of prewar intelligence but not how the administration presented it in public -- required than 20 sessions for members to agree on a final text. Phase Two, he said, could take as long.

The staff, he said, has prepared draft reports for the senators to work on that relate to two other parts of the Phase Two report -- prewar intelligence on what would happen in postwar Iraq; and how the prewar assessments of Iraq's weapons programs compared with what was uncovered after the war by the U.S. Iraq Survey Group. That group of CIA and Pentagon experts found no evidence that Saddam Hussein had weapons of mass destruction immediately before the U.S.-led invasion.

Democratic Sens. John D. Rockefeller IV, left, and Carl M. Levin said the probe will need time and careful attention.