"Who's." As in a contraction of "who has..." "Whose" is the possessive form, which you used correctly in the poll question.
None is likely to hemorrhage voters in any significant amount due to a scandal that weren't already disinclined to vote for them in the absence of a scandal. Pretty much everyone that's prone to hate Clinton already does, mostly for ancient reasons; her current behavior only serves to reinforce and remind. Those who are left are undead, glossy eyed zombies who think she can bring back the bygone 1990s, right down to every prosperous detail. People who are drawn to Obama are mostly those who are tired of bloodsport politics, so any scandal that besets him is likely to be blamed on someone else. After the Wright bit broke, it was Hillary's negatives that spiked by about ten points (while Obama's stayed the same). And that was even before her Bosnia whopper blew up in her face. McCain's "supporters" don't seem interested in him enough to care one way or the other. He seems to be many Democrats' second choice though...of the three.
Honestly no one has had any really terrible scandals or dirt come out about them. I'd vote "none of the above" but you didn't give us that choice.
