Now that Jeb is out of the race, people are talking about where his support goes. He had 8% in South Carolina -- perhaps that could be added to the Establishment favorite Rubio, and suddenly he's at 30% and within striking distance of Trump. Ditto for Kasich's support when he drops out. Carson's support would more likely go to Cruz.
Trump has already said that some of that support will go to himself. It's not as though the supporters of non-Trump candidates are so overwhelmingly anti-Trump that they won't vote for him, even when he's so clearly the front-runner in the polls, popular vote, and most importantly the delegate count. There will be an "if you can't beat 'em, join 'em" bloc that will boost his numbers, too, not just those of his rivals.
But what if a good chunk of them don't even bother voting, with the departure of their favorite candidate, and even entire class of candidates -- the Nice Guys (TM)?
Think of what a hardened fringe group they are -- to be holding out for Jeb this late in his abysmal campaign. They are not merely Establishment voters, they are so deluded that they thought Jeb of all people was their one true prayer for victory. Anyone more pragmatic, who might have been juggling Jeb around back in July, should have already moved on to Rubio.
Let's consider their choices.
They won't go for Kasich or Carson since these are niche candidates, and the former Jeb supporters already tried a niche candidate that didn't work. If they choose anyone at all to support now, it'll be one of the main three. (And even if they did go for another niche candidate, that simply delays the inevitable for when the last niche nice guy drops out.)
They could try Rubio, but if they were delusional for Jeb, they probably can't get past Rubio's lack of experience, lack of pedigree, lack of avuncular personality, etc. Plus Rubio stabbed his former mentor in the back, and that mentor was their favorite pick. They might not be able to forgive.
They would probably not go for Cruz -- he's part of the Establishment, but from the evangelical wing rather than the financial elite wing. Like Rubio, he has little experience, doesn't come from a proven dynasty, and has a creepy personality, all of which matter to Jeb supporters. He's too slimy for all but the most hardcore apocalyptic / evangelical voters.
And they could go Trump, if only to support the winner.
None of these three seem awfully likely, so perhaps these hardcore Jeb supporters will simply not show up to the polls this year. They prize candidates who have lots of political experience, some level of accomplishments to point to, probably with executive experience, politically connected, not a creepy weirdo personality, niceness and decorum matters more than substance, and so on. They might just write off the 2016 GOP race, as it exists now, as a clown-filled circus with no more appealing choices left.
More or less the same conclusion can be reached for the former hardcore Kasich supporters. And similarly for the hardcore Carson supporters, with Cruz being the only hopeful recipient. However, just like with Jeb supporters having trouble forgiving Rubio for stabbing Jeb in the back, hardcore Carson folks might have trouble forgiving Cruz for lying about Carson getting out of Iowa and stealing a good number of his votes.
So maybe a good amount of these supporters will simply not vote at all. Remember, they're not just "the kind of people that Jeb / Kasich / Carson appeals to," but those who were so devoted to their niche candidate that they stuck it out far beyond any realistic chance they had. These supporters all wanted a niceness candidate, and they're left with the tough-toned Trump, the weasel Cruz, and the slippery foam party backstabber Rubio. "It's become too much of an impolite circus, I won't be dragged down into the mud, so I'll just sit it out this time."
If these former supporters of niche candidates decide not to vote, it benefits Trump in two ways.
First, if Jeb / Kasich / Carson supporters don't join some other candidate's supporters, then the numerator for each remaining candidate stays the same. Nobody gains, nobody loses. Trump benefits by the others not gaining new supporters (numerator).
Second, if Jeb / Kasich / Carson supporters are no longer included in the total count of all voters, they shrink the denominator, which is now made up only of Trump / Cruz / Rubio supporters. When the denominator gets smaller, the fraction gets larger. Trump's share of actual voters (not hypothetical voters) rises a little bit. So does the share for Cruz and Rubio, but not by the same degree because Trump has the largest numerator.
A simple numerical example:
Say there are only 10 supporters in a state, and that they could vote for Trump, Cruz, Rubio, Kasich, Carson, and Jeb. And suppose their support was similar to the polling and early primaries -- 3 for Trump, 2 each for Cruz and Rubio, and 1 each for Kasich, Carson, and Jeb.
Suppose that the niche supporters are so demoralized and disgusted by the remaining viable candidates that they simply don't bother voting.
Then that leaves 3 for Trump, and 2 each for Cruz and Rubio. Same numerators as before. But now there are only 7 voters in total, not 10. Smaller denominator.
With all six candidates to choose from, Trump's popular vote would've been 30%, 20% for Cruz and Rubio, and 10% for the three niche candidates.
With the niche candidates dropping out, and their supporters leaving in disgust along with them, Trump's popular vote share is now 43% (3/7), with 29% (2/7) each for Cruz and Rubio. All of the major candidates increased their popular vote share, but Trump gained 13 points while the other two only gained 9 points. Before, Trump enjoyed a 10-point lead over the other two, while he now enjoys a 14-point lead. Finally, Trump is now much closer to the majority threshold of 50%.
There are two ways in which Trump could come closer to getting a majority of the popular vote -- by converting more of the former niche supporters than Cruz or Rubio could convert, or if they simply dropped out of the electorate.
If you know anyone who's supporting one of the niche candidates, do your best to resonate with their hopelessness of the clown show that the primary race has become, and ask rhetorically is it even worth voting in the primary with only these three weirdos left to choose from? Maybe just sit it out until next time, or the general.
Getting them to sit it out will be much, much easier than trying to convert them to Trump of all candidates. Remember, these are the hardcore "niceness" voters. And it has the same effect -- boosting Trump's share of the actual voters.
It will be hard to evaluate how likely the niche voters are to stay in the electorate, and if so, who they're switching to. But I suspect a decent amount will be so demoralized by the prospect of choosing a tough guy, a weasel, or a backstabbing robot, that they may just sit out the primary this time around and hope for better choices next time. That only helps Trump climb his way toward 50% in the popular vote, which is crucial for the many proportional states where 50% wins all the delegates.
Usually it's the Trump supporters who would be sitting out the primary and the general, which boosted the numbers for the Establishment candidates. Now that we're coming out of the woodwork, it may be having the same effect on the Establishment supporters, sending them to sulk on the sidelines. They deserve it for all the decades they've crowded out a majority-friendly candidate and electorate, and moved farther and farther toward extreme niche positions -- whether on the country club yuppie side or the doomsday cult side.