Democrats began 2020 at Buttigieg, then went hard left with back-to-back Bernie.

When the party was most desperate to find a candidate who could make Donald Trump a one-term president, that’s what its first three nominating contests came up with.

Nothing against Pete Buttigieg or Bernie Sanders, but it’s also why the party is resetting the order in which states vote. Well, that and an embarrassing inability to count in Iowa.

If the Dems were smart, they would put South Carolina first on their list. Not just in the South, but in the nation.

Going back to 1980, this state has been considered something of a horse whisperer in presidential politics. In 40 years, only one person has won the South Carolina Republican presidential primary and not gone on to get the nomination.

Sorry, Newt.

A little more quietly, S.C. Democrats have done just about the same. In 1992, when other states were agog over Paul Tsongas and Tom Harkin, the Dems here instead chose Bill Clinton. In 2008, the state’s overwhelming support for Barack Obama in a crowded, viable field proved that an African American candidate could play well in the South.

And, in 2020, when the Dems seemed poised to give the nomination to a semi-socialist — to the delight of lefties, Republicans and apparently the national media — South Carolina said no, we want Joe Biden.

As some party insiders here like to say: “Some states pick candidates. South Carolina picks presidents.”

There’s some truth to that, and it’s a lesson national Democrats could stand to learn — even before their regularly scheduled November shellacking.

The thing is, it’s not that complex or difficult to understand. It’s mainly just common sense.

“South Carolina Democrats might be in a minority in the state, but they have a better sense of where people are at,” says Lachlan McIntosh, a Charleston-based Democratic political consultant. “They are more moderate than Democrats in other parts of the country, more diverse. We have folks in urban, rural and — increasingly — in suburban settings. They are good at not only picking the best candidate, but the most electable.”

That’s the key, and being in the minority here seems to help that perspective. As McIntosh notes, Dems here live surrounded by Republicans, and know which candidates are likely to be most palatable to their neighbors across the aisle.

As one Democrat said months before the 2020 primary: “I like Harris, but I’m voting for Biden. Because he can win.”

In their book, “First in the South: Why South Carolina’s Presidential Primary Matters,” College of Charleston professors Gibbs Knotts and Jordan Ragusa provide ample empirical data to decode this phenomenon: The state’s Democrats — surprise, surprise — are demonstrably more conservative than their national counterparts.

As Knotts says, S.C. Democrats tend to be older, more religious, less white, less male and less liberal, and more concerned with the economy and health care than their fellow Dems across the nation.

Basically, more attuned to the leanings and interests of a nation that is still largely center-right.

Phil Noble, a political consultant and former president of the South Carolina New Democrats, says that’s mostly a result of demographics. The earlier primary states have few African American voters, who can make up more than half the primary electorate here. And S.C. Democrats, black and white, understand what plays across the country.

“We separate the wheat from the chaff in terms of electability,” Noble says.

That’s a pretty good barometer, something that a party often lagging behind in fundraising could use to get the most bang for its buck. South Carolina is small enough that retail politics can have an effect, it’s more diverse than the other early primary states, and its media markets are affordable enough that most serious candidates can participate.

We just tell ’em whether they have a chance.

Of course, the Democratic National Committee knows all this because its chairman is Orangeburg native (and former U.S. Senate candidate) Jaime Harrison. The president also knows, because he’s the most recent beneficiary of South Carolina’s prognostication.

Still, there’s big money involved — early primaries are a huge economic boon — so changing the order of nominating states will be a huge fight. New Hampshire even has a state law that says it gets to go first.

But S.C. Dems should make their case while they have folks in charge who are apt to listen. Trav Robertson, the state’s Democratic Party chair, told The Post and Courier’s Nick Reynolds that they certainly will petition to hold onto their slot as an early primary state.

Frankly, they should aim higher — for their sake, and the party’s.

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