Quite right.  But, that was a rather exceptional case, and not how Presidents and VPs are normally elected.  It's plan B or C, not plan A.  

Think of it this way: Tony Blair was elected Prime Minister (and Labour leader) in a similar sense that Nancy Pelosi was elected Speaker of the House.

Ok.  I can try to think of it that way.  It's just compartmentalized in my head in such a way that I want to say "But the legislature and executive and the party apparatus are all very different things, with different responsibilities..."  (Yes, Pelosi is in line for the Pres. but like I said, that's a worst-case-scenario backup plan.)

"Pretending that you already know the answer when you don't is not actually very helpful." ~Migeru.