The case for an Obama third term, a.k.a. a Hillary Clinton presidency, just suffered a major blow.

Indeed, Friday’s jobs report (or lack-of-jobs report) is just the thing Clinton feared most when she launched her presidential bid: namely, that Obamanomics, which boils down to the bizarre notion that higher taxes, more regulation and class warfare actually work, would begin to fully implode while she was forced into defending it on the campaign trail — or risk losing the president’s endorsement.

The sickeningly weak job creation during the month of May (just 38,000 jobs when economists expected closer to 150,000) doesn’t mean the economy is “officially” heading to a recession. But it’s yet another sign we could be heading in that direction.

Sure, the unemployment rate fell to 4.7 percent. But that’s only because more people stopped looking for work: The labor-force participation rate fell to a level right out of the malaise of the 1970s.

The May slowdown in job creation (the slowest since September 2010), meanwhile, is coupled with tepid wage growth and comes on the heels of a barely growing economy for the first quarter of 2016. (GDP of .8 percent which, I guess, is better than nothing, but not by much.)

Even worse: April’s weak job growth of 160,000 was revised down to just 123,000. Yes, there was a Verizon strike, but during past “recoveries” (as President Obama likes to call the economy under his watch), such intangibles didn’t present themselves as near-existential economic threats.

They were merely blips on an overall radar screen of green.

The political implications of all of this, to use a quote from Clinton’s GOP challenger, Donald Trump, are yuuuge. The former first lady and Obama secretary of state has always had a love-hate relationship with President Obama’s hand-me-down economy.

Out of fear of alienating voters who might turn to her lefty challenger for the Democratic nomination, Bernie Sanders, she has to pay lip service to the real economic hardships Americans are feeling thanks to the business environment created by her old boss. And yet she needs her old boss for that all-important endorsement. So as bad as things are, she must make the case they would’ve been worse without Obamanomics.

Trump should easily exploit this. To do so, he’ll have to take the occasional break from focusing his fire on Hillary’s “crooked” past.

He’s not wrong, of course, about Clintonian sleaze. But charges of corruption never seem to stick to the Clintons, because most Americans seem to accept their amoral behavior as the price of their competency.

The problem facing Hillary as the Obama economy goes south is that she’s looking less and less competent trying to attack and simultaneously defend it.

In the end, the price of an Obama endorsement will be voters associating her with his absurd economic theories that produced what the numbers showed us on Friday: an economy and job market that are barely growing and, most worrisome to Hillary, a possible recession.

Of course, things could improve; the latest GDP report and Friday’s poor job-growth numbers can always be revised upward. The Verizon strike may indeed have been the catalyst for the lousy jobs report, and businesses may be about to hire like there’s no tomorrow. And Trump could say something really stupid that would alienate even more possible supporters.

But the economic numbers could also get worse — a notion that’s no longer whispered even among super-cautious Wall Street analysts who don’t want to do anything to spook skittish investors.

Case in point: Barclays bank on Friday said that risks of a near- to medium-term recession have risen enough to put out a warning note on the subject.

Given her vast network of supporters on Wall Street (and the source of much of her lucrative speaking fees and wealth), Clinton knows those risks as well as anyone, I am told.

And that means she knows they are the biggest risk to her chances of becoming president.

Charles Gasparino is a Fox Business senior correspondent.