If the Hillary/Obama race stays close, just what will be the deciding factor(s) for the superdelegates? And what margin of delegate count will be large enough for them to refuse to overturn? 50? 100? 200?

Today's NY Times has a front page story on the superdelegates and the following quote gets at answers to my above questions:

“If we get to the end and Senator Obama has won more states, has more delegates and more popular vote,” said Representative Jason Altmire, Democrat of Pennsylvania, who is undecided, “I would need some sort of rationale for why at that point any superdelegate would go the other way, seeing that the people have spoken.”

It's likely that if the race is very close, it won't be a matter of just the delegate count, but rather a confluence of convincing items coming together to tip the scale. Notice Altmire mentions a brief list: more states, more delegates, and more popular vote. When you hear Obama supporters on the TV or radio review what he's won thus far in the primaries, they literally recite these three things, so it would appear to me that many in Obama's camp are already aware of this feeling from superdelegates or they know that by driving home stats beyond just the delegate count will undoubtedly sway their thinking.

This quote from another superdelegate, Sen. Sherrod Brown: “It’s the overall popular vote, it’s the overall delegates, it’s who is bringing energy to the campaign, it’s who has momentum...." Which candidate does that sound like, Obama or Hillary?