The sucker quotient is not a forever thing. Once people start to ask questions, then doubt, then lose confidence, it is very difficult to regain any lost footing.
I think the revelation of the Lynch story was such that at first it was hard to believe. "It's a made up story by the Bush haters..." But more and more accounts started coming out - accounts that could verify each other, with no WH rebuttal. More and more, the disillusionment set in. And the heros of the story are still the same - the young military. The villains have changed, however, and tha's important.
So the stage was set for the Iraq-Niger story to come out, with participants willing to give their names, rather than "sources." One thing added to another starts to make a cumulative effect., and then it starts rolling.
Bush today made a statement that discussion about the Iraq -uranium business is over, closed. Finished. (He wishes.) Meanwhile, Tenet assuming the responsibility is interesting, particularly in view of the fact that the stories are already out there about the CIA, other intelligence, foreign intelligence warning the WH to tread very carefully. So, by inference, Tenet suggests there was pressure brought to bear upon him.
The latset Washing Post/CBS Poll shows evidence of crumbling belief in the administration. Will they be able to shrug this off? I don't know. Although many of the teflon Reagan men are still there, it's not the same.
http://www.washingtonpost.com/wp-srv/politics/polls/vault/stories/data071103.htm?nav=hptop_ts