I wish I'd thought of this months ago.  There's one question that we really need to ask all of the leading Democratic Presidential contenders:

"In light of the GOP's willingness to filibuster everything that moves, what's your next move when 41 GOP Senators block cloture on your entire legislative agenda?"

I think we'd learn a lot from the answers, if we had the opportunity to ask the question.  It would be good to see who talks about forcing actual filibusters and who doesn't.