“Sex and the City” actress Cynthia Nixon is the new flavor of the month as the hard left searches for a challenger to Gov. Andrew Cuomo.

“There are a lot of people who would like me to run,” the B-list actress told NBC’s“Today” show while refusing to rule out a candidacy . (A lot? Maybe in Park Slope and the Upper East Side, but in Utica and Poughkeepsie — doubtful.)

True, her Hollywood ties give her name recognition and access to celebrity funding. And even unknown Zephyr Teachout won a third of the primary vote against Cuomo in 2014.

But Nixon has one big problem: Her core issue — “more equality” in New York school funding — is bunk.

Yes, she concedes, New York spends more on schools under Cuomo — $6.1 billion more, in fact, a 31 percent hike. “But the only reason that is true,” she says, “is because we spend so much on kids in our wealthiest districts.”

Wrong, wrong, wrong.

As the Empire Center’s E.J. McMahon noted recently on these pages, new Census Bureau data show that even New York’s lowest-spending school district spends 6.4 percent more than the national average.

In fact, every single district in the state ranks in the top 40 percent in nationwide per-pupil spending, and the vast majority are in the top 20 percent.

New York City, subject of a new lawsuit, topped the nation’s urban and suburban districts. And Syracuse, the other focus of the litigation, ranks in the top 10 percent.

Nixon is right that “we’ve got a real problem on our hands” when it comes to schools — though it has little to do with money. But try telling that to someone who’d run with the enthusiastic backing of the Cuomo-hating teachers unions.

If anti-Cuomo Dems really want a serious challenger, there’s Syracuse Mayor Stephanie Miner. We suspect she has a far better command of the issues.