With Congress set to begin hearings this week into prewar intelligence on Iraq (search), senators are trying to come up with some consensus on how to proceed with a formal review.

On Sunday, Senate Intelligence Committee chairman Pat Roberts (search), R-Kan., held out the possibility of open hearings -- a key demand of the Democrats -- "if we think that is warranted."

As lawmakers debated the congressional reviews on the weekend television talk shows, Roberts offered another possible concession. He said hearings would likely be followed by a classified report as well as a public report, something the Democrats also have called for.

The closed hearings of Roberts' committee would consider what information President Bush (search) used to build his case against Iraq.

The format overrules Democrats' demands for a more formal investigation with extensive questioning of witnesses about why prohibited chemical and biological weapons have not been found and accusations that some evidence cited by the administration has proved false or misleading.

Republicans suggested last week that such a probe could become politicized or harm national security. They instead favored customary oversight hearings by the Intelligence and Armed Services committees; the Senate Armed Services panel already has begun closed hearings.

Sen. Carl Levin of Michigan, the senior Democrat on Armed Services, opposed the GOP approach. "We need a thorough, bipartisan investigation," he said on CBS' "Face the Nation," where Roberts also appeared.

The doubts that have been raised about some of the prewar weapons assessments go to the "heart of our intelligence," Levin said. "Is it objective, or has it been shaded, has it been stretched by the intelligence community to reach some conclusion?"

He complained that Senate Republicans are not working and consulting with the Democrats on how to move ahead with the intelligence reviews. Senate GOP lawmakers should adopt the more conciliatory working spirit in the House, where both parties' intelligence committee leaders have agreed on a similar review, he said.

The House Intelligence Committee also will start its hearings this week with two closed meetings, and open hearings will follow if appropriate, panel members have said. The inquiry will include staff interviews of intelligence personnel and updates on efforts to find weapons of mass destruction.

The House panel's top Democrat, Rep. Jane Harman of California, said there's a real need to ensure that reports from the intelligence community matched the strong rhetoric from the administration in the run-up to the war.

Harman said it is too early to say whether the administration hyped or manipulated intelligence on weapons of mass destruction in order to justify pre-emptive military action. "We're going to find that out," she said on "Fox News Sunday."

Bush and other administration officials maintain that Iraq had an active weapons program and that time will bear that out. More than two months have passed since Saddam Hussein was routed, and weapons of mass destruction have not been found.

According to a new CBS News Poll, six in 10 Americans say it is important for the United States to find the illegal weapons.

Forty-four percent of those polled said Bush officials overestimated the extent of the Iraqi weapons stores -- and of that group, over two-thirds said the administration exaggerated the weapons threat. That sentiment appeared not to have harmed Bush politically, with his job approval still at 66 percent.

The poll of 841 adults was taken Thursday and Friday and has an error margin of plus or minus 3 percentage points.