Here’s a revealing — and disturbing — new poll that bears on the current gang fight among leftists for the soul of the Democratic Party and its 2020 presidential nomination.

Almost half of Americans in a new Gallup Poll believe that socialism would be a good thing for the United States to have. Almost half (43 percent). A good thing.

Democrats like Bernie Sanders driving that party to the left may be on to something for a winning theme in next year’s vote.

Today, a bare majority (51 percent) says socialism would be a bad thing. That number is 11 points higher than it was in a Roper/Fortune survey three-quarters of a century ago.

But those taking a more favorable view of socialism is also up — by fully 18 points since 1942. Back then, more than a third (34 percent) had no opinion on the issue. Today, only six percent have no opinion.

As the numbers in favor of socialism have increased, that may be because the popular definition of socialism has also changed. It’s not connected now so much with failed regimes like Venezuela’s with hyperinflation, starvation and crime.

Today’s definition of socialism, according to Gallup’s research, finds “nearly one in four now associating the concept (of socialism) with social equality and 17% associating it with the more classical definition of having some degree of government control over the means of production.”

Here’s a startling reminder of where the Democratic Party has moved since the centrist days of Bill Clinton. “A majority of Democrats have said they view socialism positively in Gallup polling since 2010, including 57% in the most recent measure in 2018.”

So, this is more than a slogan this time around. Hence the Trump reelection campaign driving the “Never Socialism” meme in speeches all the way down to bumper stickers and T-shirts.

Another major shift in Americans’ political opinion and expectations. In 1949, nearly three-quarters (72 percent) thought that during the next half-century the world’s nations would shift toward democratic governments.

Today that number has dropped to 57 percent.

In 1949, only 14 percent of respondents saw the world’s nations shifting toward socialist governments in the en suing 50 years. Today, 29 percent think that.

The new Gallup Poll also asked if Americans would prefer free market or government controlling various sectors of society. Free market won out there in most sectors such as wages, wealth distribution, tech innovation and the overall economy.

However, respondents came down in favor of government control in two areas: environmental policy and protecting online consumer privacy.

Take that Facebook.