As the president’s popularity plummets, Democrats are beginning to decouple from the Biden Train, right under the noses of Republicans on whom Americans are counting to avoid a derailment.

A recent AP-NORC poll found 85 percent of American adults believe the nation is on the wrong track, and the logic — if not all the polls — indicate they ought to be able to deliver a rebuke to President Biden in November.

Republicans are thrilled, failing to recognize that by focusing blame foremost on the president, they lay the groundwork for his fellow Democrats to escape culpability for steaming us into Socialist Gulch.

Far-left policies have resulted in skyrocketing inflation, historic crime levels, a wide-open border, and foreign policy failures. So now Democrats are scapegoating Mr. Biden, lamenting his age and trademark haplessness, turning Shakespeare on his head: The fault lies not in ourselves but in the stars.

If a red wave washes ashore, we can expect them to adopt “Anybody But Biden” right along with Republicans. 

Last week’s New York Times/Siena College poll finds 64 percent of Democrats already prefer another candidate in 2024, and the Wall Street Journal signaled this theme in its headline, “The Beltway’s Case of Biden Remorse.”

It’s not, though, the Beltway that’s feeling regret. It’s the American people, and the reason is hidden in plain sight: Democrats used Mr. Biden’s centrist schtick as a Trojan Horse to sneak in their disastrous agenda.

The left puts its vision of America’s transformation ahead of any one man, so they’ll load up Mr. Biden’s trunks with blame for all the pain of the last two years and let him take them with him when he leaves the White House. 

Then a new engineer — say, the governor of California, Gavin Newsom, or Vice President Harris — will continue chugging along into the ditch where leftists have taken “utopias” like Venezuela and North Korea. 

With Democrats, to quote the Who song “Don’t Get Fooled Again,” it’ll be, “Meet the new boss, same as the old boss.” 

This shell game will work if Republicans let it, accepting the premise that once we should just move on, and that once the oldest president in history shuffles off the scene, things will improve under fresh leadership. It’s the same notion behind the absurdity that “real communism has never been tried,” which would come as a surprise to Lenin, Mao, and Castro.

In reality, the Silver Streak will keep careering away from the constitutional values that made us the strongest and most prosperous nation the world has ever known. Over the weekend, this emerging theme gave birth to a Business Insider story, “If Not Trump vs. Biden in 2024, Then Who?”

We may well avoid a 2020 rematch, but if we do, does anyone expect Democrats to let the Republican standard-bearer decouple from Mr. Trump? Of course not. They’ll declare that Mr. Trump’s policies are Republican policies. It’s the smart play, ensuring the whole party bears the stigma, not just one man. 

Democrats created a caricature of President Hoover a century ago with this in mind, turning his name into a synonym for bad governance. Like the old sitcom, they handcuffed every Republican candidate to Hoover for as long as he was in living memory, later swapping in President Nixon, President George W. Bush, and now Mr. Trump.

When Republican commanders-in-chief are popular, however — like Presidents Reagan and Eisenhower — Democrats take pains to say they would oppose today’s GOP. As governor of New York in 1929, Franklin Roosevelt even declared, “I think it is time for us Democrats to claim Lincoln as one of our own.”

By agreeing to play this game, and even cheering Democrats who join them in criticizing Mr. Biden, Republicans aren’t just wasting a political opportunity: They’re setting themselves up to fail at confronting the boxcar of crises facing the nation, by honing in on personality rather than policy.

Republicans may win by not being Mr. Biden, but unless they handcuff every Democrat to the socialist train as it heads off the cliff, they’ll miss the switch we need at the next junction — and fail to get us back on a track to the America we know and love.