Personally, I would rather have a President who protects our country when its in danger rather than someone who becomes paralyzed into inaction because they cannot find a document that "plainly demonstrates in unambigious, open language" the connection between clandestine terrorist groups.
Iraq harbored numerous known terrorists, some of whom were wanted by America and other countries for past atttacks.
Iraq also supplied scientists and other assets to various programs ongoing in other countries, such as Libya, which has just come clean with its past intentions while turning over vast amounts of evidence to British and American authorities.
Would you prefer to have waited for a nuclear bomb blast in Atlanta or a sarin gas attack in Chicago before we acted??
I would too. But then again I suspect you and I understand the subtleties of Al Qaeda/Iraq ties rather better than the average American. Those are the folks who must be persuaded, and I'm not convinced that the Administration can easily do so in the absence of hard, incontrovertible and tangible proof.