For the Democrats, America did not begin in 1776 but more like 1966. From that mentality has come a perpetual purge in which no American tradition is safe from censure. The Democrats can’t rest until post-1960s liberalism becomes the only acceptable political philosophy in America.

We’re told by prominent Democrats that companies like Chick-fil-A don’t deserve to operate and organizations that quote the Constitution belong on “extremist” lists. Democrats goad companies into boycotting the NRA and demand that judges drive mild-mannered Christian bakers out of business.

But all of this radicalism comes at a political price. Voters have consistently rejected Obama’s vision of a “fundamentally transformed” America. His presidency was a disaster for the Democrats, causing them to lose a record number of seats at the federal, state, and local level. None of these defeats, however, have caused the Democrats to question their intolerant liberalism. Instead, they have hardened it and made their contempt for American tradition even more obvious. Look at how much time they spend on symbolic displays of ideological rectitude, even during a crucial election year.

The Democrats are far more interested in condemning the country than running it. As if to punctuate that point, they applaud NFL players who protest the American flag while treating law-abiding gun owners like Nazis. At one time, the members of the party most inclined to such outré views were called “San Francisco Democrats” and they stood on its margins. Now they monopolize the party and even purge each other, as Dianne Feinstein learned last weekend.

Delegates voted strongly against her re-election bid at the California Democrats’ convention. According to news accounts of this “snub,” the Democrats felt the need to punish Feinstein for the nebulous offense of insufficient liberalism.

“People are frustrated,” one delegate was quoted as saying. “She’s the most senior member and we value that, but as the most senior member, you’ve got to give it to Trump. She has the power to challenge him, and she doesn’t always do that.”

Her opponent, Kevin de León, declared, “I’m running for the United States Senate because the days of Democrats biding our time, biting our tongue and triangulating at the margins are over.”

Too true. The party has no interest in broadening its appeal or playing any constructive role in government. That it sees Dianne Feinstein as a bigger problem than Nancy Pelosi illustrates yet again that it has gone past the point of no ideological return. Another measure of that is the absurd boomlet for Kamala Harris, who is now cast as a probable presidential candidate. One of the nastiest members of the Senate, Harris epitomizes the far left’s control over the party.

Hillary saw half the country as “deplorables.” But for the San Francisco Democrats, that is too cautious an estimate. They see most of the country as deplorable. Hence, their boycotts grow ever more expansive, extending to conventional positions once contained in their own platform. In this frenzied atmosphere, Feinstein’s bona fides as a gun confiscator couldn’t even win her any appreciation. No deviation is too small for the Democrats to police at this point.

In this race to the left, the Democrats are leaving the center wide open for Trump. As the party cleaves to the coasts — symbolized perfectly by a House leader from San Francisco, Nancy Pelosi, and a Senate leader from New York City, Chuck Schumer — the phenomenon of Trump Democrats can only grow. Much of his agenda, after all, rests upon a nationalism once shared by both parties. The reflexive opposition to anything Trump proposes, no matter how blameless, makes the Democrats look extreme, not him.

Feinstein’s problem wasn’t her age. A party that idolizes Bernie Sanders could live with that. No, it was her small, barely perceptible, ideological hesitations that turned her into a target. Those were enough to make her a worrisome “pragmatist,” maybe even a deplorable.

The impatient, feverishly ideological, mood of the Democratic Party lends itself to squabbling over the most minute and unimportant differences. It has no interest in governing, not even at the “margins,” as Kevin de León puts it. It simply wants to oppose and vindicate its resentments. It is a party that cheers Maxine Waters and boos Feinstein — a party, in other words, perfectly content to remain in the minority.