On Sunday, Senate Intelligence Committee chairman Pat Roberts, a Kansas Republican, 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 demanded.
The closed hearings of Roberts' committee would consider what information President Bush 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.
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.
Sen. Carl Levin of Michigan, the senior Democrat on Armed Services, opposed the Republican approach. "We need a thorough, bipartisan investigation," he said on CBS News' 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?"
Mr. 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.
The lone evidence so far of any illegal activity — two trailers found in northern Iraq that may have been biological weapons factories — has been brought into question by a new British report.
While no traces of illegal germs were found in the trailers, the CIA concluded last month that they were likely mobile bioweapons factories.
In a report of the find, the CIA said it was, " the strongest evidence to date that Iraq was hiding a biological warfare program."
But according to Britain's Observer newspaper, a British government report contends that the trailers are not used to produce deadly germs but instead to make hydrogen for balloons used by artillery units to gauge wind speed and direction.
The CIA report acknowledged this possibility. "Hydrogen production would be a plausible cover story for the mobile production units," it read. But the doubts about the trailers could be embarrassing for both Mr. Bush and Prime Minister Tony Blair, who have referred to the "mobile labs" as questions have arisen over whether the primary rationale for war was based on solid evidence.
So far, those questions have not tainted the president's popularity. According to a new CBS News Poll, 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.
But the chance for political fallout remains. According to the poll, six in 10 Americans say it is important for the United States to find the illegal weapons. Two-thirds of those polled said they think the administration exaggerated the weapons threat.
The gravest political threat to the president would be if a Democratic candidate were able to turn the administration's treatment of prewar intelligence into an issue.
It would be especially potent if that candidate linked Mr. Bush's Iraq policy to supposed failures in the war on terrorism, which is the hallmark of the Bush presidency to date.
The campaign of Massachusetts Sen. John Kerry is getting help from a former National Security Council analyst who quit just before the war because he felt the anti-terror efforts were harmed by the plans for invading Iraq, The Washington Post reports.
Rand Beers tells The Post that the war siphoned manpower and money away from the fight against al Qaeda and fractured the global alliance formed to destroy Osama bin Laden's terror network.
Beers says the claims that Iraq hoarded weapons of mass destruction were based on "pretty qualified" evidence.
"I continue to be puzzled by it," he told The Post. "Why was it such a policy priority?"
Also Monday, the European Union said it could accept going to war to stop the spread of weapons of mass destruction — but only after exhausting all diplomatic means and only with U.N. approval.
At their regular meeting here, EU foreign ministers endorsed a strategy to combat the proliferation of nuclear, biological and chemical weapons that provides for military action as a last resort against governments or terrorists.
The EU's first such strategy stems from the Iraq war, which revealed significant differences between Washington and European capitals over how to deal with weapons of mass destruction.
Meanwhile, the one-time Iraqi ambassador to the United Nations, Mohammed al-Douri, told BBC World that Saddam's government had told him the illegal weapons were destroyed in 1991-92.
"I would right now believe that the Iraqi government was not lying, and we are now waiting for the American and British to present evidence on these weapons of mass destruction."