The White House is facing increasing pressure to set up a full independent inquiry into alleged intelligence failures in the run-up to war in Iraq.
No banned weapons have yet been found in Iraq
All Democratic presidential contenders support an inquiry, and this weekend former Vermont Governor Howard Dean is expected to demand an investigation.
Republican Senator John McCain has also broken ranks to insist on a full probe.
President George W Bush has said he, too, wants to "know the facts", but not that an inquiry will be set up.
The BBC's Justin Webb in Washington says the White House is moving - albeit at a slow pace - towards accepting that claims made about Iraqi weapons before the war may have been wrong.
However, CIA analysts did not have their judgements on the issue coloured by undue pressure from the White House, a US newspaper says an inquiry has concluded.
As this year's presidential election campaign gathers pace, the Democrats are keen to turn the issue into a political cause celebre, says our correspondent.
Mr Dean, a long-standing critic of the war, is expected to demand a full, independent inquiry during a tour of a TV studios this weekend in a bid to reinvigorate his presidential campaign.
Influential Arizona Republican John McCain's decision to join the calls for an inquiry has also put pressure on the Bush administration.
Mr Bush told reporters on Friday: "I want the American people to know that I, too, want to know the facts."
He said he wanted to be able to compare what was found by the Iraq Survey Group - about 1,400 people searching for Iraq's alleged weapons - with what had been thought before the war.
National Security Adviser Condoleezza Rice on Thursday became the first senior member of the Bush administration to acknowledge publicly that the data used as the key argument for invading Iraq may have been wrong.
Her admissions were seen as a painful necessity after ex-head of the Iraq Survey Group, David Kay, told Congress he did not believe there were significant stockpiles of banned weapons in Iraq before the war.
Howard Dean is turning up the pressure
Our correspondent says the demands for an inquiry are now a serious issue in American politics - and one the president will have to address.
But he says the lack of WMD is regarded as a separate issue to whether the war was justified.
On Friday, Mr Bush reiterated his view that ousted Iraqi leader Saddam Hussein had been a "danger".
"We dealt with the danger, and as a result, the world is a better place and a more peaceful place, and the Iraqi people are free," he said.
The Washington Post reported on Saturday that a Congressional and CIA investigation had found no evidence that the judgements of its intelligence analysts were affected by political pressure.
Richard Kerr, an ex-deputy CIA director who led the agency's review of its pre-war assessment on Iraq, said analysts' work was consistent over many years.
"There was pressure and a lot of debate... that's quite legitimate," he is quoted as saying. "But the bottom line is, over a period of several years," the assessments "were very consistent".
In Britain, pressure is also growing on UK Prime Minister Tony Blair to set up an inquiry into the pre-war intelligence. His office echoed his American allies in saying the war was necessary to stop an imminent threat from an Iraq armed with weapons of mass destruction.
Mr Blair is expected to be challenged on why he is sticking by the WMD arguments when he appears before a committee of senior members of parliament on Tuesday.
A spokesman for Mr Blair has dismissed calls for an inquiry into the gathering of intelligence and said the Iraq Survey Group should be given time to finish its work.