In the wake of the airstrike on Syria, everyone took notice of how negatively Trump's most hardcore supporters reacted, whether they struggled to rationalize the airstrike after their initial gut rejection of it, or jumped off the Trump train entirely, or fell somewhere in between.
Generally speaking, those who are newer to voting Republican were the most initially turned off. Those who were content, perhaps eager, to vote for Romney last time or God forbid McCain before that, had an easier time rationalizing or outright cheering on the strike. It's just the kind of move that Romney or McCain or Bush would have done, and indeed these figures suddenly found respect for a man they'd been maligning for years.
It would be an electoral mistake to discount these new Republican voters, or even shove them out the door as fair-weather friends. If only partisan Republicans vote next time, Trump will get wiped out just as bad as McCain and Romney did.
The GOP and Trump in particular needs these new Republican voters, and a large part of his appeal to disillusioned Independents and Democrats was shaking up the Establishment status quo. He was keen to emphasize the change in priorities he sought for foreign policy -- Iraq War was a disaster, Assad's a bad guy but he's fighting ISIS so let him stay, let's get along with Russia, and why do we serve as South Korea's military for free while they steal all of our manufacturing plants?
Certainly we should not believe that every new Republican was pissing their pants like some of the alt right Twitter people, but that is simply the tail of a distribution that had shifted in the "less approving" direction. If 20-something red-hats are pissing their pants, it means that the average Trump fan had also moved in that direction of feeling let down, even if not so extreme.
YouGov conducted a poll after the airstrikes to gauge support across various demographic groups. Since all of the questions are variations on the same theme (interventionist vs. not), the pattern of responses is similar across the questions.
On the whole, the key demographic groups who put Trump over the top on Election Day are the most ambivalent or turned off by the strikes -- Independents compared to Republicans, lower income rather than higher income, and Midwest region compared to the South or Northeast (the West is also highly opposed, but West Coasters didn't vote for him).
The first question asks at the most general level, is your view that "It’s best for the future of our country to be active in world affairs," or "We should pay less attention to problems overseas and concentrate on problems here at home"? Independents chose the America-first answer 44-37, while Republicans were about split at 45-46. Those with family income under $50K chose America-first at 44-40, those with $50-100K at 45-42, and only those with more than $100K gave the globalist response at 51-37. Midwesterners were the most America-first at 48-42, Westerners 39-38, Southerners slightly pro-globalist at 44-42, and Northeasterners even more globalist at 43-37.
Look through the other questions if you want, but the same basic pattern shows up. Since they allow "Not sure" answers, look at the responses that go definitively against the Establishment consensus. For example, on the question of supporting the airstrikes, the somewhat/strongly oppose response is more common in the Midwest (34%) and West (38%), than in the South (31%) or the Northeast (28%).
So which demographics resonated the most with the strikes? Wealthy Republicans (or Democrats) from the Northeast, AKA the NeverTrumpers who will sabotage any of the America-first agenda, and will never vote for him in 2020. Middle-class Independents from the Midwest, i.e. the people who put him in the White House, are the most unsettled by the apparent abrupt shift from campaign promises.
Nobody appreciates that the culture wars are largely fought within the elite level, and that working-class people don't pay any mind to abortion, tranny bathrooms, white privilege, etc. They are focused on bread-and-butter issues because their basic needs are less secure. It's only those who don't have to worry about income, food, housing, and so on, who have the time and mindset to indulge in post-material concerns like gay marriage, tort reform, etc.
Foreign policy is almost an entirely elite obsession -- as the data show, most working-class people don't give a shit about the rest of the world (not that they wish it any specific harm), and want that money spent right here on things they can actually enjoy. Roads without potholes, universal healthcare, whatever.
Only the yuppies have all of that lower stuff covered on Maslow's Hierarchy of Needs, and turn their minds more toward airy-fairy things like "America's greatness in the world," namely taking more and more of the world into an American sphere of influence.
Being managerial types, they diddle themselves as they vicariously imagine themselves as the Chief Executive over a sprawling geopolitical empire, and how many more mergers and acquisitions can be done by the end of the term. They're the ones who ejaculated when Trump launched missiles at Syria, who have resisted joining America Inc. and must be crushed in a hostile takeover if they will not voluntarily be added to our portfolio of client states.
Ditto for regional differences: the Establishment along the East Coast is obsessed with "America's standing in the world," while Midwesterners are too removed from the centers of power to care that much.
The reality is the exact opposite of the "bread and circus" narrative about why we're bombing some place again for no reason. It's not to give the proles something explodey to cheer about while they wave an American flag. It's a status upgrade for the courtier class, who imagines itself presiding over an even greater range of exotics looking up to them (the "people" we're going to "liberate" from the target of our bombing).
Trump will have to take a stronger stand against the Deep State forces that are pushing him to change his America-first foreign policy, if he wants to reassure his electoral base that the Syria strike was just a fluke. Not just promises to go to a smaller magnitude in the current direction, but a change in direction back toward true-Trump. The more that foreign policy comes to resemble George W. Bush: The Resurrection, the closer he comes to being a one-term President.
It's true that his base will value all of the seismic moves he is making on the economic front, from instantly killing the TPP to bringing back more plants. But unless there is rapid re-industrialization within four short years, those efforts may not be enough to offset the further and growing drain on our economy and on our entire society if the neocons continue to get their way on major foreign policy fronts.
It's also true that immigration was a yuge motivation for Trump's hardcore voters, but this was not so important in the Rust Belt, since it has remained relatively unscathed by mass immigration.
I'm not predicting a loss for Trump if the Deep State dictates foreign policy, but it comes into possibility, and he would definitely lose at least one of the Rust Belt states where it was close (MI, WI, or MN). And that would almost certainly mean no third consecutive term for whoever comes after Trump in 2024, although three in a row is hard for anyone to pull off. But now more than ever, we can't afford for Howard Dean or Corey Booker to take back the White House in eight years.