[dllthomas]

Narrowly regarding "But I don't believe that, because some government leaders and some political candidates are essentially shameless.":

First, there is a tremendous difference between (having already been exposed) choosing to run in the face of that difficulty (possibly not showing sufficient shame, to be sure, but dealing with what is effectively a sunk cost) and choosing to take (or postpone taking) that blow in the first place.

Second, even if there are congresspersons who wouldn't comply in the face of blackmail, are there enough or are they insufficiently identifiable that they can't simply be avoided?

Note that I'm not saying that I think blackmail of many in congress by the NSA is hugely likely, I'm just not sure your reasoning is sound.