Used to be that Republicans running for president had the monopoly on unknowns, also-rans and non-politicians who would suddenly step up and deliver standout performances in debates.

It happened in 2008, when Mike Huckabee shot into the top tier with cracker barrel humor and cornpone wisdom and the libertarian crackpot Ron Paul ranted about foreign aid.

In 2012, various candidates from the far-right Congresswoman Michelle Bachmann to a restaurant executive named Herman Cain to the long-out-of-office Rick Santorum would electrify the party for a couple of weeks before fading back into the pack and leaving Mitt Romney the last man standing.

Well, Tuesday night in Detroit, the veteran New Age motivational speaker Marianne Williamson hit it out of the park and brought the Democratic Party into the Nutcase Era.

The key problem afflicting America, in Williamson’s view, is a “dark psychic force” that is weaving a racial divide. It is the cause of white nationalism. That racial divide is causing an “emotional imbalance” that is interfering with human thriving. And this betrays the purposes of the founding fathers, who brought America into being to allow us all to have “possibilities.”

To most of us elitists, this either sounds wacko on its own terms or is dismissible as a semi-pagan illiterate translation of classic Christian thinking about the devil’s role in ordinary life. But we dismiss the power of this approach at our peril. These are key themes not only through American history, but also ideas that have played a significant role in the Age of Oprah.

Williamson has been speaking in this way to gigantic audiences for close to 40 years, under the East Coast radar. And you know what? She’s really good at it. And she brought real feeling and passion to the most visceral issue for Democrats at the present moment. She essentially said that racism and white supremacy are nothing less than demonic and that saving America from their evil is a moral task.

“I want a politics that goes much deeper,” Williamson concluded. “I want a politics that goes to the heart. . . . We need to override dog whistles . . . We need to love each other, love our democracy.”

Williamson won the debate going away, if only because her performance was so unexpectedly effective. But the enduring impact of the debate was really the way in which Elizabeth Warren may have finally curb-stomped her fellow leftist, Bernie Sanders.

Warren was as focused in her demagoguery as I’ve ever seen her. She did not bother to answer pointed questions about whether her spending plans would require raising taxes on the middle class (they would) but instead threw out more argle-bargle about how millionaires and billionaires would just do it. She said not wanting to do big things was “spineless.”

Alas for Sanders, he was unfortunately reminiscent of Austin Powers — not as an international man of mystery, but as someone coming out of a 30-year deep freeze and discovering that he was “having difficulty controlling THE SOUND OF MY VOICE!” Yell, yell, yell, yell.

If you wanted substance, you got it. The first hour was mostly taken up with a lively and interesting debate on what is and is not realistic when it comes to health care spending and insurance plans.

The problem is that the candidates (John Delaney and Steve Bullock) who said Warren and Sanders were offering pie-in-the-sky plans that would rob 180 million people of the private insurance they might actually like are completely out of step with their own party.

But keep an eye on that “dark psychic force” Williamson warned us about. It might have legs.