re: Ah but that's different
I see. You're talking about the "we were all fooled by Bush" scenario. Unfortunately, that doesn't hold up much better, since based on their remarks in the late 1990s they were all apparently fooled by Bush while he was governor of Texas.
The hard fact is that almost everyone believed the same things about Saddam and his weapons that Bush did.
The usual response then is "Well, but the Democrats didn't actually DO anything about it." There are several ways that can be interpreted, but most of them still lead to the conclusion that Democrats can't be trusted with serious matters of national security.