I think it could be said that Hillary Clinton and Donald Trump are incredibly lucky to be running against each other. Both of them are deeply unpopular candidates among the general public. Neither Hillary nor Trump is viewed favorably by the majority of Americans, and seeing as both are household names, these numbers probably won’t change much. Both have considerable opposition within the ranks of their respective parties which could perhaps be grabbed up by the opposing side(#nevertrump on the right and #bernieorbust on the left). And for both of them, the single biggest driving factor for people voting for them is to stop the other from becoming president. The real question that is relevant to the general election is what effect, if any, will crossover voting and abstaining from voting have on the election results in November.
— Scott Adams (@ScottAdamsSays) June 11, 2016
Since Trump has been the Presumptive Nominee for longer than Hillary, we can have a bit more concrete idea of this. Now, it’s typical that when a candidate wins their primary, they get a boost in their general election polling. Even in the final weeks before the Indiana primary, there was polling showing Trump hanging by a thread in states as red as Georgia and Utah. The very fact that people were turning out to vote for Ted Cruz and John Kasich after they were mathematically eliminated from winning a majority gave credence to the idea that the #NeverTrump people were serious. But as we can see, Trump did end up getting a boost, at the same time that Clinton fell quite a bit. Trump is still behind, but given the simple fact that there are more Democrats than Republicans in America, Trump seems to have basically consolidated the party behind himself.
So, how did Trump manage, despite being so disliked, to get Kasich and Cruz voters on board? The first and more obvious reason is that Republicans really, really hate Hillary Clinton. You could have thrown any of the 17 people who ran in the republican primary and the party would have coalesced to some extent. But didn’t a ton of high profile republicans really not want him to be the nominee? In the answer to that question is the reason that Trump got about as much of a boost as any generic republican would, and it signals some trouble on the horizon for the Clinton camp.
Of course GOP establishment types don’t love him. But he’s their guy now, whether they like it or not. Establishment Republicans are probably registered Republicans, not independents. They are, at the end of the day, party-line voters. While most GOP candidates would embrace the base and ignore certain wings that have lower turnout, Trump did the opposite. He embraced ideas that are against conservative orthodoxy such as his opposition to free trade and endless wars. While doing this to align himself more to the center than average, he also embraced some more extreme positions that are more popular among conservatives than most Republican politicians would care to admit. By embracing positions on both sides of the fringes of the Republican party, he set himself apart and set himself up to widen the base later with certain leftist positions. Once he won, all he needed was to consolidate people who were going to vote republican no matter what anyways. Somebody like Paul Ryan would hope for somebody a bit less volatile to support, and may withhold his endorsement for a while, but the idea that he would pick Hillary Clinton over Donald Trump is absurd. Perhaps he has alienated some True Conservatives, but there weren’t actually that many of them anyways, and he has much more room to grow in states like Pennsylvania than any other Republican would have.
Now, on the other side, Hillary Clinton is in the exact opposite situation. Instead of starting with the outsider vote and then having the regulars show up out of habit, she has been shown to be the ultimate insider whose coalition is already composed of the most loyal Democrat voters. Almost all of the difference between Bernie and Hillary’s polling numbers against Trump comes from the fact that almost all Hillary voters would vote for Bernie if pressed, but almost a third of Bernie supporters say they would rather not vote for Clinton. Now, Bernie supporters were maybe less likely to turn out in the first place, but young voters are a large group for democrats when they do show up, and were a crucial part of the coalition that brought Barack Obama over the top in 2008. Democratic turnout in the primary is way down already from what it was in 2008, so without a high youth turnout, the democrats could have a harder time against Trump, who has excited many demographics who are less likely to vote for mainstream republicans.
As Nate Silver pointed out, Bernie supporters are disproportionately registered independents rather than democrats. It follows that there is a large number of them who are voting out of anti establishment bias rather than a genuine love for democratic socialism. If current polls of them are right, Hillary will have a hard time wrangling them all up, whereas Trump is in a great position to win over significant amounts of them.
Of course, any republican candidate would be fighting an uphill battle this election season due to demographic issues, but if Trump plays his cards right, he can crush Hillary by capitalising on her unpopularity with the people on the fringes of the democratic party.