Ten years ago I, for one, had the distinct impression that those Democrats agreeing with the Bush-Cheney Administration that Saddam was hiding WMDs were going out of their way to avoid noticing that they were only being given claims, not actual evidence, supporting the charges. This was manifestly the case with Secretary of State Colin Powell's now infamous UN presentation. There was no real evidence presented at all. It was like the Emperor's New Clothes story come to life with politicians and much of the public raving how Powell had "nailed" Saddam dead to rights. The sad truth is that most politicians and many citizens, regardless of party, wanted the war on Iraq and were prepared to believe almost any charge that could justify it. The evidence of WMDs was not really there and the contrary evidence was ignored:

A special BBC Panorama programme aired on Monday night details how British and US intelligence agencies were informed by top sources months before the invasion that Iraq had no active WMD programme, and that the information was not passed to subsequent inquiries.
It describes how Naji Sabri, Saddam's foreign minister, told the CIA's station chief in Paris at the time, Bill Murray, through an intermediary that Iraq had "virtually nothing" in terms of WMD.
Sabri said in a statement that the Panorama story was "totally fabricated".
However, Panorama confirms that three months before the war an MI6 officer met Iraq's head of intelligence, Tahir Habbush al-Tikriti, who also said that Saddam had no active WMD. The meeting in the Jordanian capital, Amman, took place days before the British government published its now widely discredited Iraqi weapons dossier in September 2002.

The negative findings of the UNMOVIC inspectors, although being publicly reported were being dismissed:

The Bush administration certainly wanted to go to war, and it advanced eradication of weapons of mass destruction as the main reason. As Deputy Secretary of Defense Paul Wolfowitz has since explained, it was the only rationale that was acceptable to all parts of the U.S. administration.

The WMDs argument also carried weight with the public and with the U.S. Congress. Indeed, in the autumn of 2002 the threat seemed credible. While I never believed Saddam could have concealed a continued nuclear program, I too thought there could still be some biological and chemical weapons left from Iraq's war with Iran. If not, why had Iraq stopped U.N. inspections at many places around the country throughout the 1990s?

However, suspicions are one thing and reality is quite another. U.N. inspectors were asked to search for, report and destroy real weapons. As we found no weapons and no evidence supporting the suspicions, we reported this. But U.S. Defense Secretary Donald Rumsfield dismissed our reports with one of his wittier retorts: "The absence of evidence is not evidence of absence." -- Hans Blix head of U.N. weapons inspections in Iraq (UNMOVIC) in the lead-up to the 2003 invasion.

Please ignore the claims made by some advocates of the war that they are not to blame because "everybody" believed Saddam was hiding WMDs. True, many did believe but on a matter as serious as going to war they were inexcusably negligent and gullible.