The Democratic Party bears little resemblance to the themes Barack Obama and Hillary Clinton embraced in the 2008 primaries.

The parameters of marriage — “between a man and woman,” in Obama’s words — have now transmogrified beyond gay civil unions to legal gay marriage to transgendered fixations.

Obama once protested that he was no king who could open the border and grant amnesties by fiat. Yet his view of immigration has metamorphosed well beyond Dreamers into Democratic candidates going into Mexico to escort aliens unlawfully into our country — and 500 sanctuary jurisdictions in which federal immigration law is all but null and void.

In a nanosecond, Betsy Ross’ iconic colonial flag, which once emblazoned the backdrop of the 2012 Obama inauguration, has become a racist icon.

ObamaCare has abruptly morphed into “Medicare for All” — including illegal aliens, eligible as soon as they cross the border.

The socialist party has absorbed what is left of the old Democrats. At first, the progressive old guard in Congress, like good Girondists, found the revolutionary carnivores useful in reducing the ranks of the Trumpians, the Tea Party, Reagan Democrats, old Perot voters and the white working class to the inanimate status of “deplorables,” “irredeemables,” “clingers” and “dregs” — and with them, the bigoted, racist, sexist, nativist, classist, homophobic and xenophobic GOP.

Certainly, House Speaker Nancy Pelosi, Senate Minority Leader Chuck Schumer and a few geriatric sympathizers such as Sens. Dianne Feinstein and Dick Durbin enjoyed the progressive feasting on the ancien régime — especially the unity offered by shared hatred of the obviously soon-to-be-impeached, deposed, exiled and discredited President Trump.

But revolutionary carnivores are rarely sated. Once they run out of easy hostile targets, they get hungry and as cannibals start to eye their own.

We have already seen that autophagy in the initial primary debates in which all the major Democratic presidential candidates shouted out the most outlandish agendas possible in a desperate effort to ensure that no rival could possibly pose more to their left.

Poor, condemned Joe Biden ­renounced almost everything he once believed in and yet still was reduced metaphorically to screaming for his life on the guillotine stage that he was a revolutionary after all!

All the while, Pelosi, Schumer and a host of old Democrats enjoyed the new energy that was ­directed against the evil Trump. To revolutionary cheers, 1 million illegal aliens crossed the border in the first six months of 2019. The media-left-wing-celebrity nexus sought to devour Trump by myriad means.

Once all these efforts to destroy Trump failed, so too waned ­superficial revolutionary solidarity. In the manner that Robespierre and his Committee of Public Safety guillotined naïve Girondists, so, too, “the Squad” of Reps. Alexandria Ocasio-Cortez, Ilhan Omar, Ayanna Pressley and Rashida Tlaib are now damning Pelosi as a racist.

Again, Pelosi is old, and in the way, and is a target of her party’s quick adoption of her own identity politics. What were the Pelosi generation, the left-wing journalist crowd and the professoriate thinking when they harangued nonstop about the forthcoming irrelevancy of supposed old, white dinosaurs? That thereby, such woke white liberals somehow had purchased exemptions from the very executioners whom they had helped create?

What is the next wrinkle in this revolutionary trajectory to the guillotine? Pelosi, now playing the role of a Thermidor, hinted the other day that the Squaders still represent just a few thousand constituents in gerrymandered, minority, left-wing districts.

Pelosi is on to something. Just as the Jacobin agenda was nihilistic, so are the fantasies of the adolescent Squad. No sane American would ever willingly embrace the ludicrous Green New Deal, the abolition of the Electoral College, the end of Immigration and Customs Enforcement, extending the franchise to 16-year-olds, cancellation of college debt, free tuition, reparations, a wealth tax or legal infanticide.

Mostly, the Jacobins frighten the old progressives. They empower Trump. They make what is left of the Never Trump Republicans look even more ridiculous. Ultimately, they are racists, who self-define by their appearance and their ethnic backgrounds in an ever more integrated, multiracial country in which the effort to transcend those Neanderthal considerations was largely the story of the last century.

Where will it all lead? To the metaphorical collective Democratic guillotine unless some sane Democrat stands up and says no more — and learns that the revolutionary mob might prefer to guillotine the guillotiners.

Victor Davis Hanson is author of “The Case for Trump.” Adapted from American Greatness.