As the Democratic presidential contest reaches the third state, what began as a coronation is now an exciting dead heat. Yet by one measure, Bernie Sanders is ­already a clear winner.

Regardless of whether the senator from Vermont captures the actual nomination, he has won the future of the Democratic Party.

Sanders is demolishing the last remnants of the old order, as represented by Hillary Clinton and her split-the-difference triangulation. It is Sanders, not she, who is the true heir of the radical politics of Barack Obama.

Calling a paradigm shift is like forecasting a recession — predict it often enough and you’ll eventually be right. Yet the developments unfolding before our eyes suggest the Democratic Party is undergoing a massive change. And a 74-year-old socialist is the architect.

A major piece of evidence is the enormous youth vote he attracts. In Iowa and New Hampshire, he beat Clinton by about 70 points — 84 percent to 15 percent — among voters under age 30. And despite the nasty demands by Madeleine Albright and Gloria Steinem that women must support Clinton, Sanders got 82 percent of the young female vote.

By contrast, Obama in the 2008 primaries typically beat Clinton among young people by about 20 points. With studies showing that most people stay in their first political party for many years, the young, ultra-liberal voters who turned out for Obama, and who are being joined by the Sanders wave, could dominate the party for a generation.

Click to read Goodwin’s full column in the New York Post.