As you may have heard by now, Donald Trump and Hillary Clinton will enter the general election as the two most disliked major presidential candidates in modern history. But just what effect will that have on voters? A new Reuters/Ipsos survey shines some light on the answer, and it's not pretty: Nearly half of both Trump and Clinton supporters say their primary motivation isn't putting their preferred candidate in the White House — it's keeping the other one out of it.

While the percentages are roughly comparable, that doesn't mean the number of people planning to vote against Clinton (as opposed to voting for Trump) is the same as the number who plan to vote against Trump (as opposed to voting for Clinton). Hillary leads in a still-technically hypothetical general election matchup with the celebrity billionaire by about 9 points in Reuters' tracking poll, suggesting there are considerably more not-him voters out there than not-her ones at the moment — something that makes sense given that for all of Clinton's many problems, she's not a dangerously unstable demagogue who wears a gold-plated fig leaf emblazoned with the words "unpredictability" and "winner" on it.

Still, the sizes of both of those numbers are striking.

To be fair, the general dislike of both candidates can be explained partly by negative partisanship, which has been increasing for some time. In 2014, Pew researchers found that over the past two decades the share of both Republicans and Democrats who have a very unfavorable opinion of the other party has more than doubled (from 17 percent to 43 percent for Republicans, and from 16 percent to 38 percent for Democrats). And those numbers understate just how passionately those intense partisans feel about the opposing side. Among those who stated a very unfavorable opinion, a clear majority said that the other party is a "threat to the nation's well being." If you think that, it's easy to see why you would be more fearful of the other party's nominee than you are hopeful about your own.

Still, that the current state of electoral politics — as polarized as they are — doesn't entirely explain just how unpopular Trump and Clinton are among voters right now. If it did, you'd expect the number of Americans who strongly dislike him or her to largely be offset by a corresponding number of those who strongly like him or her. But, as FiveThirtyEight's Harry Enten demonstrated, that's not the case. Since 1980, even the most unpopular nominees didn't head into the general election with a net-strong favorability rating — that is, the percentage with a "strongly favorable" minus the percentage with a "strongly unfavorable" one — below negative-10. Clinton's, though, is currently roughly twice that, while Trump's is more than four times it. (Hillary should thank the electoral heavens every morning that she's up against someone who cancels out so many of her weaknesses.)

It also stands to reason that the ranks of both competing oh-good-god-anybody-but-him/her camps will grow during the six long and nasty months between now and Election Day.

Those anti-Trump primary voters who end up voting Republican in November anyway will almost certainly do it to keep Clinton out of the White House.

Similarly, many of the Bernie Sanders diehards who ultimately come around to Hillary will probably do so first and foremost in the name of stopping the Donald. A contest between two candidates who are so disliked, then, could come down to which one can do a better job of convincing Americans of the dangers of their rival. On that front, Hillary seems to have a sizeable head start.

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