Clarification on: "to follow up 9/11 w/ an attack like that would make them look weakened to the core"
What I mean by that is that they likely wont pull a spain or london for their next attack, they will do something on equal footing or worse than 9/11.
Also, the president is not completely to blame on this issue. The senate has failed us as well on the border:
"Vote To Increase Border Agents fails (But Senator George Allen Voted for More Agents)"
http://www.freerepublic.com/focus/f-news/1443753/posts
If and when a major attack is traced back to our wide open southern border, the blame will be 100% his.