Want to know why Hillary Clinton’s campaign is struggling, despite the fact that the Democratic National Committee is doing everything possible to rig the primary process in her favor?

Her performance this week on “Equal Pay Day” tells the story: her stilted, college-lecture-hall style, her cartoonish “real-life” examples, and — most of all — the utter disconnect between her public proclamations and her personal behavior.

Equal Pay Day should be Hillary’s time to shine. This is the holiday feminists dreamed up to raise awareness about the “wage gap.”

They want the public to believe that American workplaces are overwhelmingly sexist to build support for massively expanding the government’s role in the economy. They imply that their favorite Department of Labor statistic compares two coworkers, one male and one female, showing women receive just 77 percent of the man’s pay.

Reality is quite different. In fact, careful analysis shows that the gap shrinks to just a few percentage points when relevant factors such as the number of hours worked each day, industry, education and years of experience are taken into account.

Even the liberal groups behind Equal Pay Day usually grudgingly acknowledge in their fine print that the real unexplained wage gap is much smaller than advertised. But that doesn’t stop them from carrying on with their Equal Pay Day traditions and pushing the bogus 77-cents-on-the-dollar mantra.

No wonder Hillary Clinton uses every Equal Pay Day to make her case: She’s counting on women feeling aggrieved and wanting to defy the patriarchy by voting a woman into the Oval Office to set things right.

In fact, Clinton launched her official presidential campaign last year on Equal Pay Day as a call to arms to women to help her shatter the ultimate glass ceiling.

It hasn’t gone exactly as planned. Today, Clinton struggles to connect with Democratic primary voters — including women assumed to be her base. Gaining on Clinton, Bernie Sanders is now essentially tied with her among all women and strongly favored by younger women. That’s a big change from the double-digit leads she once took for granted.

Her ten-minute remarks this week at an Equal Pay Day event sponsored by the online job and recruiting network Glassdoor were a monotonous rerun of every other speech she’s given on the topic.

Plus, her public lamentations about the scourge of sexism that haunts America’s business world were overshadowed by the headlines produced by a Daily Caller investigative report.

Turns out the Clinton Foundation has a “Mad Men” era wage gap of its own: Male executives made 38 percent more than female executives. Yep, apparently, the Clinton family foundation exemplifies the things Democrats say they hate: the Foundation drastically short-changes the female help.

Voters are likely also to be wide-eyed at the sheer numbers involved, with the Foundation’s supposed public servants earning salaries that triple the average US household income.

This isn’t the first time Hillary Clinton has been exposed as an equal-pay hypocrite. In August, the Washington Free Beacon revealed that women on Clinton’s campaign staff make less than the men, and her Senate office staff also had a pay gap larger than the national average.

I’m sure the Clintons have good explanations for these pay disparities. I bet the men working at the Foundation and on Mrs. Clinton’s staffs have had different roles, longer hours and more job experience. Yet that’s exactly why there’s a wage gap throughout the entire economy, and why the whole premise of Equal Pay Day is bogus.

Hillary Clinton seems to assume that voters won’t notice that she rakes in hundreds of thousands of dollars from big banks when she’s lamenting the influence of Wall Street or that she pledges transparency while hiding her government correspondence in a private e-mail server. She trusts that women will just applaud her supposed “lifetime” of work to advance the cause of women, and ignore how she and her husband have actually treated real-life women throughout their careers.

But Hillary shouldn’t bet on it. Especially in this election, voters are seeing right through such hypocrisy. And that’s the biggest problem of all for the Clinton campaign.