Both the result of the Constitution and long-practiced custom the office of the Vice-President has devolved into something of an afterthought. Because of this, potential Vice-Presidents are too casually selected despite the cliché that the Veep is but a heartbeat awy from the Presidency! In my opnion, this is playing chicken with the Ship of State! Think of this: President Paul Ryan or President Joe Biden.
Or can you imagine Sarah Palin in that office? Or John Edwards or Dick Cheney? Scared enough? Actually, the problem is that in the selection of the Vice-President running mate it's done as sort of an afterthought, and for the wrong reasons.
1) To begin with, the President and Vice-President run as a ticket: if you want one candidate as President, you are stuck with the Vice-President running mate. And, possibly due to brain farts, reasonably good Presidential candidates can come up with lulus as running mates.
2) In recent times, the Vice-Presidential candidate is deliberately chosen by one person: the Presidential candidate. Not by a separate process in the primaries, not by vote of a political convention. That is chutzpah, in my opinion!
3) The wrong criteria are used: to nag a state's electoral votes, to serve as a sop to one wing of the party that was disappointed with the outcome of the primaries, to semibalance the ticket into being a more national one, and so forth.
4) The office is regarded as a joke, even as far back as a hundred years ago.
5) The office is regarded as a waiting room for future Presidential candidates while the current office-holder serves his or her term.
Therefore, it seems to me that there should be separate voting for the Presidency and Vice-Presidency. Parties should be able to make nominations, but there should be no necessary end product that both are of the same party! I could live with that. And by candidates specifically running for that office and being elected to it,
And, who knows, since the Vice-President is also a member of the cabinet, the separate election of this person would be a plus!
And it would not be the end of the world if the President and Vice-President could be of separate political parties.