Also, people who had nothing to do with Bush Administration believed the same thing. A couple random quotes (please note that many predate Bush's election as President and can't even be blamed on "Bush told CIA to mislead every other dumb politician in USA and foreign leader" usual argument):
“Even today, Iraq is not nearly disarmed. Based on highly credible intelligence, UNSCOM [the U.N. weapons inspectors] suspects that Iraq still has biological agents like anthrax, botulinum toxin, and clostridium perfringens in sufficient quantity to fill several dozen bombs and ballistic missile warheads, as well as the means to continue manufacturing these deadly agents. Iraq probably retains several tons of the highly toxic VX substance, as well as sarin nerve gas and mustard gas. This agent is stored in artillery shells, bombs, and ballistic missile warheads. And Iraq retains significant dual-use industrial infrastructure that can be used to rapidly reconstitute large-scale chemical weapons production.” — Ex-Un Weapons Inspector Scott Ritter in 1998
“The community of nations may see more and more of the very kind of threat Iraq poses now: a rogue state with weapons of mass destruction, ready to use them or provide them to terrorists. If we fail to respond today, Saddam and all those who would follow in his footsteps will be emboldened tomorrow.” — Bill Clinton in 1998
“Saddam’s goal … is to achieve the lifting of U.N. sanctions while retaining and enhancing Iraq’s weapons of mass destruction programs. We cannot, we must not and we will not let him succeed.” — Madeline Albright, 1998, Clinton's Secretary of State.
“(Saddam) will rebuild his arsenal of weapons of mass destruction and some day, some way, I am certain he will use that arsenal again, as he has 10 times since 1983″ — Clinton's National Security Adviser Sandy Berger, Feb 18, 1998
“Iraq is not the only nation in the world to possess weapons of mass destruction, but it is the only nation with a leader who has used them against his own people.” — Tom Daschle in 1998
“As a member of the House Intelligence Committee, I am keenly aware that the proliferation of chemical and biological weapons is an issue of grave importance to all nations. Saddam Hussein has been engaged in the development of weapons of mass destruction technology which is a threat to countries in the region and he has made a mockery of the weapons inspection process.” — Nancy Pelosi, December 16, 1998
“What is at stake is how to answer the potential threat Iraq represents with the risk of proliferation of WMD. Baghdad’s regime did use such weapons in the past. Today, a number of evidences may lead to think that, over the past four years, in the absence of international inspectors, this country has continued armament programs.” — Jacques Chirac, October 16, 2002
"I am absolutely convinced that there are weapons...I saw evidence back in 1998 when we would see the inspectors being barred from gaining entry into a warehouse for three hours with trucks rolling up and then moving those trucks out." -- Clinton's Secretary of Defense William Cohen in April of 2003
“[W]e urge you, after consulting with Congress, and consistent with the U.S. Constitution and laws, to take necessary actions (including, if appropriate, air and missile strikes on suspect Iraqi sites) to respond effectively to the threat posed by Iraq’s refusal to end its weapons of mass destruction programs.” — From a letter signed by Joe Lieberman, Dianne Feinstein, Barbara A. Milulski, Tom Daschle, & John Kerry among others on October 9, 1998
“This December will mark three years since United Nations inspectors last visited Iraq. There is no doubt that since that time, Saddam Hussein has reinvigorated his weapons programs. Reports indicate that biological, chemical and nuclear programs continue apace and may be back to pre-Gulf War status. In addition, Saddam continues to refine delivery systems and is doubtless using the cover of a licit missile program to develop longer- range missiles that will threaten the United States and our allies.” — From a December 6, 2001 letter signed by Bob Graham, Joe Lieberman, Harold Ford, & Tom Lantos among others
“In the four years since the inspectors left, intelligence reports show that Saddam Hussein has worked to rebuild his chemical and biological weapons stock, his missile delivery capability, and his nuclear program. He has also given aid, comfort, and sanctuary to terrorists, including Al Qaeda members, though there is apparently no evidence of his involvement in the terrible events of September 11, 2001. It is clear, however, that if left unchecked, Saddam Hussein will continue to increase his capacity to wage biological and chemical warfare, and will keep trying to develop nuclear weapons. Should he succeed in that endeavor, he could alter the political and security landscape of the Middle East, which as we know all too well affects American security.” — Hillary Clinton, October 10, 2002
“Whereas Iraq has consistently breached its cease-fire agreement between Iraq and the United States, entered into on March 3, 1991, by failing to dismantle its weapons of mass destruction program, and refusing to permit monitoring and verification by United Nations inspections; Whereas Iraq has developed weapons of mass destruction, including chemical and biological capabilities, and has made positive progress toward developing nuclear weapons capabilities” — From a joint resolution submitted by Tom Harkin and Arlen Specter on July 18, 2002
“Iraq made commitments after the Gulf War to completely dismantle all weapons of mass destruction, and unfortunately, Iraq has not lived up to its agreement.” — Barbara Boxer, November 8, 2002, one of the most liberal US Democratic Senators.
“The last UN weapons inspectors left Iraq in October of 1998. We are confident that Saddam Hussein retained some stockpiles of chemical and biological weapons, and that he has since embarked on a crash course to build up his chemical and biological warfare capability. Intelligence reports also indicate that he is seeking nuclear weapons, but has not yet achieved nuclear capability.” — Robert Byrd, October 2002
“There’s no question that Saddam Hussein is a threat… Yes, he has chemical and biological weapons. He’s had those for a long time. But the United States right now is on a very much different defensive posture than we were before September 11th of 2001… He is, as far as we know, actively pursuing nuclear capabilities, though he doesn’t have nuclear warheads yet. If he were to acquire nuclear weapons, I think our friends in the region would face greatly increased risks as would we.” — Wesley Clark on September 26, 2002
“Iraq does pose a serious threat to the stability of the Persian Gulf and we should organize an international coalition to eliminate his access to weapons of mass destruction. Iraq’s search for weapons of mass destruction has proven impossible to completely deter and we should assume that it will continue for as long as Saddam is in power.” — Al Gore, 2002
“We are in possession of what I think to be compelling evidence that Saddam Hussein has, and has had for a number of years, a developing capacity for the production and storage of weapons of mass destruction.” — Bob Graham, December 2002
“We have known for many years that Saddam Hussein is seeking and developing weapons of mass destruction.” — Ted Kennedy, September 27, 2002
“I will be voting to give the president of the United States the authority to use force – if necessary – to disarm Saddam Hussein because I believe that a deadly arsenal of weapons of mass destruction in his hands is a real and grave threat to our security.” — John F. Kerry, Oct 2002
“The threat of Saddam Hussein with weapons of mass destruction is real, but as I said, it is not new. It has been with us since the end of that war, and particularly in the last 4 years we know after Operation Desert Fox failed to force him to reaccept them, that he has continued to build those weapons. He has had a free hand for 4 years to reconstitute these weapons, allowing the world, during the interval, to lose the focus we had on weapons of mass destruction and the issue of proliferation.” — John Kerry, October 9, 2002
“Whether one agrees or disagrees with the Administration's policy towards Iraq, I don't think there can be any question about Saddam's conduct. He has systematically violated, over the course of the past 11 years, every significant UN resolution that has demanded that he disarm and destroy his chemical and biological weapons, and any nuclear capacity. This he has refused to do. He lies and cheats; he snubs the mandate and authority of international weapons inspectors; and he games the system to keep buying time against enforcement of the just and legitimate demands of the United Nations, the Security Council, the United States and our allies. Those are simply the facts.” — Henry Waxman, Oct 10, 2002