Republican presidential nominee Trump. Getty Donald Trump, the nastiest presidential candidate of the television era, on Wednesday night called his opponent "such a nasty woman," which was just another example of him being nasty.

Trump's nastiness is one of the reasons he will lose the election. But it's also a key reason he got the Republican nomination in the first place.

Over the last few decades, as racism and sexism have become impolite, a substantial number of voters on the right have decided politeness itself is a problem.

Trump's absolute commitment to nastiness — often taking the form of crude sexual insults of women or claims about the criminality of minorities, but expansive enough to include many put-downs of white men as well — signaled to his voters that he was one of them, a committed opponent of the forces of politeness that seek to make "regular Americans" feel guilty about "speaking their minds."

Trump, of course, prefers to frame his nastiness as a rejection of "political correctness," as do many of his supporters.

There are cases of real excesses in sensitivity norms, as you may learn if you try to wear a Halloween costume or make sushi on a college campus. But the problem with the term "political correctness" is that it does not mean anything — or rather, that it can be used to impugn whatever norms governing social discourse from which the speaker would like to be liberated.

As it turns out, most of the norms around social discourse are good ones.

For example, they include "don't call women 'fat pigs,'" and "don't categorize large chunks of nationalities as rapists and criminals," and "don't brag about how big your penis is on the stage at a presidential debate." But if you violate any of these norms and say you're just being "politically incorrect," tens of millions of boorish idiots will cheer you on.

U.S. Republican presidential nominee Trump smiles after making what he said was a major announcement, that he'd abide by the election results if he won, to supporters at a campaign rally in Delaware, Ohio Thomson Reuters

This is the Achilles' heel of any anti-PC movement: The "deplorables" are the ones with the most at stake in the fight against social norms, and their top priority is not sushi at Oberlin College.

They will end up leading any anti-PC movement that gets real political traction and turning it into one that simply seeks to destroy any notion of politeness or civility or manners. If politeness is a bar to sexism and racism, then sexists and racists will be very eager to Make America Impolite Again.

Is it any surprise these deplorable people ended up with Donald Trump, America's tackiest and nastiest business celebrity, as their standard bearer?

Fortunately, nastiness is a loser in a general election.

After this election, Republicans will need to do a lot of soul searching, probably much more than they actually will do. They ended up with a candidate whose toxic nastiness was his primary appeal. Their voter base wants a level of nastiness that general-election voters will not approve.

In 2002, after the Conservative Party in the United Kingdom lost two consecutive landslide elections, a wise member of that party warned against the danger of fueling a political party with the resentment of a minority of the population.

"There's a lot we need to do in this party of ours," Theresa May said. "Our base is too narrow and so, occasionally, are our sympathies. You know what some people call us: the Nasty Party."

The Conservatives have had a complicated history since then, one that has led to May becoming prime minister and, indirectly, to Brexit. But she was right that one essential step for winning elections again was becoming significantly less nasty — even if that meant bleeding some of their voter base to a nastier right-wing nationalist party.

After November 8, Republican leaders will have to decide whether they want to be Donald Trump's Nasty Party, or whether they will stand up to their own voters when they demand his brand of nastiness.