Here’s the signal question facing the Democrats in Washington: Does the ­Superstar Leftist Trio in Congress — Alexandria and the Supremes — truly represent the views of the party’s voters as 2020 approaches?

If they do, then the decision to capitulate last week to Rep. ­Ilhan Omar and back away from censuring her anti-Semitism was the right call politically, even if it was morally despicable.

Clearly, enough Democratic members of the House believe the trio — AOC, Omar and Rep. Rashida Tlaib — is in the right or is the vanguard, or fear the potential primary challengers the three might recruit to run against House colleagues who don’t bend their arc toward ­social justice war.

But what if they’re reading the whole situation wrong? What if the media power the Trio ­enjoys so outstrips their real ­political power that there’s little reason for the Democrats to dash madly to the left and make excuses for Omar’s disgusting Jew hatred along the way?

What gave the Democrats their majority in the House? Not the victories of AOC, Tlaib and Omar. Each of them filled a seat formerly held by a Democrat in a district with little or no Republican vote — and in the case of Tlaib and Omar, succeeded Democrats nearly as radical as they are.

Tlaib now occupies the ­Detroit seat of John Conyers, who held it for 52 years and compiled a leftist voting record second to none over that half-century.

In Minneapolis, Omar follows Keith Ellison, who was, according to govtrack.com, the most liberal member of the Minnesota House delegation.

Only Ocasio-Cortez can lay claim to having replaced a representative less progressive than she — and she did so by knocking off the astoundingly lazy Rep. Joe Crowley, who didn’t bother to protect his Queens/Bronx seat at all and lost it in a primary by 5,000 votes out of a mere 25,000 cast.

Democrats didn’t win the House in November 2018 ­because of the Trio’s victories. Their victories didn’t affect the balance of power at all. Democrats won 40 seats formerly held by Republicans.

These are the Democrats whose views and approaches to getting elected should be the talk of Washington — because if Democrats can win voters like the ones who turned the tide in 2018, they can win the presidency.

I’m talking about freshman members like Jason Crow in Colorado, Sharice Davids in Kansas, Haley Stevens in Michigan and Abby Finkenauer and Cindy Axne in Iowa.

They actually went into territory controlled by Republicans and flipped the seats blue. They did so by riding the anti-Trump wave in the suburbs and stressing Democratic-friendly issues like health care.

They are Democrats, not ­Republicans. They are pretty liberal. But they aren’t crazy, and they aren’t extreme. They figured out how to talk to voters and mobilize them.

This isn’t something the ­Superstar Trio ever had to do. Once the primaries were over, they walked into the House.

Ocasio-Cortez has the ability to blather on about the Green New Deal and the irredeemability of capitalism, because she doesn’t have to worry about persuading voters in her district who might think she is a lunatic. Omar can focus her monstrous attention on Jews for the same or similar reasons.

Politicians know what’s good for them. If Democrats in the House think they need to cater to the Trio, that belief needs to be taken seriously.

But it could also be yet ­another example of Plato’s Cave coming to Washington. The ­intimidating shadows cast by the Trio — owing in part to their own charisma and to the eagerness not only of the media but of their supporters on the left and their sharpest opponents on the right — may be far larger than the actual authority or support they have generated.

In 2020, the Democratic Party wants and needs to take back the three Rust Belt states that fell to Trump by tiny margins — Michigan, Wisconsin and Pennsylvania.

Is their task made easier or more difficult by the fact that no one knows the names of the Democrats who actually know how to win over Republican and independent voters, while ­everyone knows the names of the three extremists who have never faced a significant ideological challenge in their lives?

The answer isn’t a great mystery.

jpodhoretz@gmail.com