If this month’s election is any guide, state and local politics bode ill for progressive Dems. New York Democrats overreached, and their miscalculations are instructive for how future campaigns, especially the upcoming New York City mayoral race, can be won.

Whether because they feared for their left flanks, or because they’re deluded by enormous self-regard in an echo chamber of tweets, New York Democrats abandoned common sense in favor of radical policies that endanger our communities. So-called bail reform, anti-police measures, unrealistic housing regulations, out-of-control spending and vile rhetoric have emerged as Albany’s and City’s Hall’s routine agenda.

These reckless Democratic policies have cost us citizens, of course, but now they have also cost them — the politicians. Maybe now they’ll learn. It’ll take time to confirm results, but our local politics are showing early signs of trending back to the middle.

The full diversity of New York City includes the communities of southern Brooklyn and Staten Island, where Republicans are defeating Democratic incumbents. Congressional, state Senate and Assembly seats are flipping from Democratic to Republican. In Borough Park, the local state senator and assemblyman, both Democrats, received more votes for re-election on cross-endorsed Republican and Conservative ballot lines than they did on the Democratic line. Bay Ridge and Dyker Heights appear to have tossed out their one-term Democratic state senator and, coupled with Staten Island, booted out their one-term Democratic member of Congress.

In Staten Island, the GOP scored a huge win with the election of Rep.-elect Nicole Malliotakis. Meanwhile, a longtime state assemblyman, who is also the chairman of that borough’s Democratic Party, is fighting for his political life in a race too close to call.

The full diversity of New York City includes parts of Queens, where a Democratic assemblyman lost to a Republican and where South Asian communities elected a moderate Democratic assemblywoman over a liberal incumbent in a hotly contested summer primary.

Southern Brooklyn’s moderate ethnic and religious communities have become the foundation of the borough’s vote; their participation increased in response to the condescension of brownstone liberals and editorial boards.

I have the honor of leading the diverse union of frontline law-enforcement professionals who work where policy becomes policing. Sergeants are responsible for the cops they supervise and accountable to senior officers who set policy.

Sergeants are uniquely qualified to understand what works and what doesn’t. What we see — reality on the streets vs. politics from above — hasn’t been working. Voters have shown that they understand this truth.

Outside Gotham — in Long Island, the northern suburbs and the Hudson Valley — a similar dynamic is playing out. Democratic state senators and a Democratic member of Congress are losing their races. And open seats that self-styled Albany power brokers predicted would become Democratic are instead going red.

Law and order, public safety, balance in government, sound economic policies: These have been the rallying points for communities organizing against the hard left.

Looking ahead to the 2021 mayoral race, this year’s elections are deeply instructive. The candidate with the best shot will be the one who can balance the radical left against moderate Democrats, many of whom just voted for Republicans.

The winning candidate will have to broaden his or her appeal to those who just repudiated Albany and City Hall Democrats without alienating those who were repudiated. With several candidates running from the left, the winner will likely be someone else — a nimble moderate — who can build and maintain this uneasy coalition.

Police families, organized now more than ever and voting more than ever, will have a role in building this coalition. New York is much more than whatever the geniuses who strategized recent Democratic losses believe. New York isn’t just the Manhattan neighborhoods where lefty editorial-board members live. New York is also Staten Island and Borough Park and ethnic Queens.

Ed Mullins is president of the Sergeants Benevolent Association of the NYPD.