Why should a party benefit?

Returning to Senator Clinton's comment, I'd like to be able to say that what she was talking about wouldn't be the case if we weren't stuck under a two-party system, but in this case I don't think I can. Even if we had a no-party system, the herd instinct to rally around the leader after a "9/11" style terror attack would still work to the benefit of the leader himself, and therefore to the Executive Branch. The President, or his faction, could still exploit the herd instinct to advance a particular, partial agenda, or if the President was near the end of his term, he could use his renewed public support to promote a personal favorite as his successor. The benefit of a no-party system would be that no one in Congress would be automatically allied with the President or bound by partisan loyalty. As a result, Congress might be more likely to resist any excessive executive measures. In the present case, I'll concede that any bounce Bush or the GOP would get from another attack would be much less than that of September 2001 because more people this time will be willing to blame the government for failing to protect us. On the other hand, the U.S. is not Spain, and I doubt whether another attack would result in a wholesale repudiation of the current regime, as happened after the Madrid attacks. Not that I wish an attack to happen, but if it did, I'd like to be proven wrong in my prediction.