Politics is about addition, not subtraction.

I don’t know who first said it (the Internet offers many possibilities), but it’s an iron law of politics, not just democracy. You gain power by adding forces to your coalition, and you lose power by subtracting forces from your coalition.

That’s the lesson of the recent election results in Virginia and elsewhere across the country. But again, that’s the lesson of pretty much every election, because of that whole iron law thing. It’s not complicated.

For years now, the GOP has been losing support among its natural primary constituency — middle- and upper-middle-class suburban voters — while it has been gaining support from lower-income and working-class whites. Donald Trump cobbled together a coalition of the two, in specific swing states, to win the Electoral College while still losing the popular vote.

Trump pollster Tony Fabrizio noted just after the election that his client won by carrying five crucial counties, four in Florida and one in Michigan.

Contrary to a lot of spin from Trump and his boosters, who claim that “Trumpism” is a new ideological force transforming the country, the president owes the bulk of his victory to the simple fact that he was not Hillary Clinton — a figure who singularly unified the Republican Party. “America First,” “build the wall” and all the issues most frequently associated with Trump’s victory may have attracted some new white working-class voters to the party, but they divided (and still divide) the traditional Republican coalition.

Take Clinton off the ballot, and support for “Trumpism” — and for Trump himself — drops among traditional Republicans and plummets among Independents, moderates and, of course, Democrats.

Trump has been shedding supporters pretty much from the day he took office. A little more than a year after his election, he has unprecedentedly low approval ratings for any president, even within his own party.

Fired Trump advisor Steve Bannon, the most overrated figure in American politics, championed Republican Virginia gubernatorial candidate Ed Gillespie as proof that the “Trump agenda” is bigger than just Trump. Just days before the election, Bannon told The New York Times that Gillespie had “closed an enthusiasm gap by rallying around the Trump agenda … in Gillespie’s case, Trumpism without Trump can show the way forward.”

Gillespie lost by nine points. Suddenly the Bannonites were denouncing Gillespie as an inauthentic swamp creature who failed to embrace Trump sufficiently.

His opponent, Ralph Northam, won because suburban white voters abandoned Gillespie, either because they were turned off by his Trumpish rhetoric or simply because they wanted to protest Trump.

Trump boosters have a legitimate point that Virginia — the only southern state Clinton carried last year — wasn’t Trump country. Northam lost among non-college-educated whites by a staggering margin: 72 percent to 26 percent. But he more than made up for it among suburban college-educated whites, particularly women. Northam outperformed Clinton by five points among college graduates. He finished six points better with white college-educated men, and 10 points better with white college-educated women.

Bannon seems to believe that Republicans can afford to subtract educated suburbanites by boosting turnout from rural and working-class non-college-educated voters.

In a state like Alabama, that may be possible, given the demographics there. That’s why Bannon supported Roy Moore over Luther Strange, a more conventional and electable Republican incumbent, in the recent Senate primary. As of this writing, Bannon’s preferred candidate is mired in a scandal, as he’s been accused of sexual preying on underage girls.

Regardless, nationwide, this theory was always absurd. Majorities are determined at the margins, by candidates who can win in “purple” districts and states, by adding moderates, independents and registered voters of the opposing party. A Republican coalition that chases away significant numbers of white voters while unifying traditional Democratic voters in opposition is destined for minority status.

It’s unclear whether Bannon understands this and just doesn’t care, or whether he’s cluelessly working on the assumption that the GOP can afford to lose more voters than it gains. Either way, the Virginia election looks like the first of many defeats in elections to come, as the GOP seeks to sell off chunks of its coalition like assets in yet another Trump bankruptcy.

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