Brain Game: V for Vote

IMPORTANT NOTE: I laid a BIG egg with my original text for today's Brain Game, claiming that there were three answers when in fact there are four. But I've fixed the phrasing, so we're ready to go.

The (revised!) phrasing of the question in today's mentalfloss.com Brain Game Tuesday Test Time challenge may provide a hint to one (or two) of the four answers. Give it a shot:

Exactly FOUR last names of U.S. presidents
contain the letter V.  Name them.