Former US Vice-President Al Gore has accused the Bush administration of deliberately misleading the people about its reasons for invading Iraq.
Gore accused Bush of a fabrication over Iraq
He said Mr Bush tried to link Saddam Hussein with the 11 September attacks.
The BBC's Jannat Jalil in Washington says it was Mr Gore's most scathing attack on the Bush administration yet.
Meanwhile, Neil Diamond and Barbra Streisand are to duet for the first time in 24 years at a fundraiser for Democrat candidate John Kerry.
Streisand is due to top the bill at the fund-raising concert in Los Angeles on Thursday night, attended by Mr Kerry.
The gala concert is the first of two featuring an array of stage and screen stars aimed at raising $10m (£5.5m) for Mr Kerry's campaign.
The two shows were originally scheduled for early June, but were postponed because of the death of former President Ronald Reagan.
Mr Kerry has been campaigning in Silicon Valley in California to put forward plans to create more high-tech jobs and increase internet broadband use.
He said the US had fallen to 10th place in the world for adapting to broadband, which he described as vital to the country's economic growth, and pledged to bring internet access to every American family.
Other big names in the Democratic Party have got behind Mr Kerry, with former President Bill Clinton giving him a greater than 50-50 chance of beating George Bush.
In an interview for MSNBC cable TV news channel, Mr Clinton said the candidate was "not laying low" and "doing exactly what he should be doing".
Mr Gore accused President Bush of "intentionally misleading the American people by continuing to aggressively and brazenly assert the linkage between
al-Qaeda and Saddam Hussein".
Speaking at Georgetown University in Washington, Mr Gore said that if the administration had not lied about there being a link between Iraq and al-Qaeda, then it must have been very gullible to believe what he called the flimsy scraps of evidence that had been used to justify invading Iraq.
"Right from the start, beginning very soon after the attacks of 9/11, President Bush made a decision to start mentioning Osama Bin Laden and Saddam Hussein in the same breath, in a cynical mantra designed to fuse them together as one in the public's mind," he said.
Our correspondent says President Bush and Vice-President Dick Cheney have continued to insist that there is a link, despite the fact that the respected independent commission investigating 9/11 reported this month that it found no evidence of a relationship.
Mr Gore also said the war in Iraq had caused untold damage, not just in terms of lives lost or financial or military terms, but to democracy itself.