Failing public schools is the defining “civil rights issue of our day,” Gov. Andrew Cuomo said on WNYC Monday morning.

The governor strongly defended charter schools, saying that they aren’t a “threat” to public education, but an enhancement.

At the same time, he said public schools have failed “generations” of students in the state.

The comments come half a week after Cuomo appeared a rally for charter schools in Albany, held outside of the Capitol and only blocks away from New York City Mayor Bill de Blaiso’s own rally for his universal pre-Kindergarten plan, which backs a tax hike for those earning $500,000 and more.

Cuomo insisted to host Brian Lehrer that his proposal to fund universal pre-Kindergarten offers more certainty than de Blasio’s tax hike.

The mayor has said he wants a “dedicated funding stream” for universal pre-K in the city and a tax ensures that the program will be paid for.

Cuomo, disagrees, noting a tax can be undone.

“It’s called a law, like a budget law, and sometimes we pass a law and sometimes we undo a law,” Cuomo said, adding, “There’s nothing more certain about a tax than a normal budget bill.”

The governor’s $142 billion budget would fund universal pre-K at $1.5 billion over five years.

Needy school districts would be eligible for the first round of funding, which starts at $100 million in the coming 2014-15 budget year if the spending proposal is approved.

Cuomo and Senate Republicans so far have resisted calls for the tax hike, with GOP Leader Dean Skelos saying the surcharge is off the table.

Assembly Democrats support the tax, however, and have pushed publicly for more spending on the pre-K front.