Bush is "now intentionally misleading the American people by continuing to aggressively and brazenly assert the linkage between al-Qaida and Saddam Hussein," Gore said, during a speech to the law faculty at Georgetown University on Thursday.
Gore recalled that an independent commission investigating the 11 September 2001 attacks found in a preliminary report no "credible evidence" of cooperation between Baghdad and al-Qaida.
Gore said Bush and Vice President Dick Cheney "have decided to fight to the rhetorical death over whether or not there's a meaningful connection between Iraq and al-Qaida".
'War wasn't necessary'
"If Iraq has nothing to do with the attack or the organisation that attacked us, then that means the president took us to war when he didn't have to."
"If Iraq has nothing to do with the attack or the organisation that attacked us, then that means the president took us to war when he didn't have to"
former Vice President
Also attacking Bush's reasons for war is a new book by a CIA analyst who says that the US is losing the war against terrorism, and sticking to current policies will only make its enemies in the Islamic world grow stronger.
"Imperial Hubris: Why the West is Losing The War on Terror," written by "anonymous" is scheduled to be released on 15 July.
It is the latest book by a government insider criticising the administration's national security policies.
"Anonymous" has appeared this week in silhouette on television news programmes talking about the book. His first name is Mike and he is an analyst at the CIA's Counterterrorist Centre where he once led the unit that focused on al-Qaida leader Usama bin Ladin.
The book's premise is that US leaders are wrong to tell the public that Muslim groups attack Americans because of disapproval of the American way of life.
'Anger at policy, not lifestyle'
Instead, it is anger at specific US policies that is fuelling growing anti-American sentiment in the Islamic world, among all segments of society.
"While important voices in the United States claim the intent of US policy is misunderstood by Muslims, that Arabic satellite television channels deliberately distort the policy, and that better public diplomacy is the remedy, they are wrong," the book says.
There is deep anger across the
Muslim world towards US policies
"We are at war with an al Qaida-led, worldwide Islamist insurgency because of and to defend those policies, and not, as President (George) Bush mistakenly has said, 'to defend freedom and all that is good and just in the world'," the book said.
US policies that generate anger in the Muslim world include support for Israel, occupation of Iraq and Afghanistan, support for Russia, India, and China against their Muslim communities, and US pressure on Arab energy producers to keep oil prices low, the book said.
'Policies must change'
Unchanged policies leave America only a military option for defending itself, the book said.
"The choice we have is between keeping current policies, which will produce an escalating expenditure of American treasure and blood, or devising new policies, which may, over time, reduce the expenditure of both," the book said.
"We cannot talk or negotiate our way out of this mess; the enemy has listened for thirty years and believes US promises of fairness for Muslims have been lies," it said.
Stinging poll figures
Gore's comments, and the release of the CIA insider's book come as a new poll shows for the first time that the majority of Americans believe the US-led war on Iraq was a mistake, according to a USA Today/CNN/Gallup Poll released on Thursday.
Amid continuing violence in Iraq and questions about the justification for the war, 54% of the 1,005 Americans polled said it was a mistake to send US troops into Iraq, compared with 41% who held that view three weeks ago.
The findings mark the first time since Vietnam that a majority of Americans has called a major deployment of US forces a mistake, USA Today reported on its web site.