Hillary Clinton’s polling lead over Donald Trump keeps fading, and the pundit class has almost no clue why.

Talking heads point to everything from her lack of trustworthiness to even the color of her pantsuits to explain why the momentum is shifting away from her. But the real culprit can be found in the one issue that most acutely impacts average Americans: the flailing US economy.

Friday’s employment numbers didn’t show that the economy is falling off the cliff, but it does continue to head in the cliff’s direction, with a marked reduction in job creation. It’s further proof that the Obama economy is a dud — and so is the policy approach that President Obama employs and that Clinton would copy.

It’s also further proof that Trump still has a clear opening for attack if he can just give his obsession with immigration a break for long enough to make the point.

Just look at Friday’s job numbers. Sure, unemployment holding steady at just 4.9 percent sounds good, and the Dow is comfortably above 18,000. But a broader measure of unemployment, known by economists as underemployment because it includes part-timers looking for more steady work, remains at a more alarming 9.7 percent.

The dirty little secret is that those “official” unemployment numbers — touted by Obama as evidence that his agenda of high taxes, massive regulations and European-style socialism is working — are belied by more realistic economic statistics.

Economic growth as measured by GDP is barely existent; the amount of people in the labor force who are working or want to work remains at recent historic lows; wages are up, but barely.

The last eight years were a great time to buy stocks — thanks to the Fed’s decision to keep interest rates so low, there’s practically nowhere else to put your money. That is, if you had a job and enough disposable income to do so. Yes, this is a great economy for many wealthy investors or Silicon Valley coders. And sure, you can always find a part-time job at Wal-Mart.

As we saw again on Friday, the real data show that almost everyone else has gotten the shaft, which is why Trump remains in the race with the following caveat: He isn’t winning ground so much as Hillary is losing it.

Even as Clinton’s unfavorable ratings have skyrocketed to Trumpian levels, his poll numbers have remained virtually flat at around 40 percent. Clinton is slipping, as many Americans become fed up with her email and Clinton Foundation antics and lies about those antics.

Democrats I speak to are alarmed by this, but they (and many smart GOP operatives) still think Trump’s a long shot because he continues to forgo a sustained attack on the insipid Obama economy that Clinton would be forced to defend by virtue of her party affiliation — if, of course, someone actually attacked Democrats’ economic record and put Clinton on the defensive.

That’s part of the Trump conundrum: He has a great plan to lower taxes and cut red tape, thus creating jobs. But he almost never compares it to Clinton’s Obamanomics redux.

He harps on immigration by playing on people’s most base fears (the country’s changing ethnic makeup) without explaining why they really should be fearful: the true economic insanity that occurs when you flood the country with cheap labor that will further depress wages, not to mention the multitudes that will tap into a growing welfare state that the country can ill afford.

Following Friday’s weak jobs number, a growing number of economists are now predicting that Fed chairwoman Janet Yellen won’t raise rates until after the election. Wall Street might cheer that move (or lack of one) because cheap borrowing rates are deemed good for stock speculation, and it might seem with the Dow heading toward 20,000 that Clinton has even more wind at her back as Election Day approaches.

But the stock market has been a lousy indicator of the true state of the Obama-Clinton economy; the rich have gotten richer and the poor are working part-time at Wal-Mart. Again, if you’re a stock market speculator, you’ve done well; if your money is in the bank, well, you got hosed.

The American people, often intuitively, know this. They just need a certain GOP presidential candidate to remind them about it from time to time.

Charles Gasparino is a Fox Business Network senior correspondent.