OPINION:
Last week’s biggest political news was that Sen. Bernie Sanders has once again entered the race for president. Most Democratic Party insiders were not thrilled.
A bevy of reactions, including those from elected Democrats in South Carolina, ranged from ambivalence to outright hostility. One hot take, from a prominent South Carolina state senator, was that Mr. Sanders needs to “commit to being a Democrat in order to be taken seriously.”
There’s no better proof that Democrats missed the key lesson of 2016. Party kingmakers are too often swayed by groupthink and pack journalism, not to mention their desires for preferred outcomes. They should listen to their voters, and stop listening to themselves.
Otherwise, Democratic insiders could face their nightmare — Bernie Sanders as their nominee and possibly even president. And even if insiders actually listen to voters, the outcome might be the same.
I witnessed a similar scenario play out on the Republican side from 2013-2016, when I served as chairman of the South Carolina Republican Party and ally of the Republican National Committee.
Republican insiders spent 12 long months ignoring, downplaying and then fighting Donald Trump’s insurgent campaign, instead of trying to understand his supporters and synthesize their energy and ideas.
Now, it seems, Democrats will do the same to Mr. Sanders. I’m no fan of the ideas Mr. Sanders promotes, but it’s hard to deny his coalition is energized. Within 24 hours of Mr. Sanders announcing, his campaign raised $5.9 million from more than 223,000 small-dollar donors.
It’s also hard to deny the modern Democratic Party, especially its millennials, is enamored with the big government, socialist policies espoused by Mr. Sanders. Yet, Democratic Party insiders would rather ignore reality than understand what it means and change course. They’re playing right into Mr. Sanders’ hands.
Conventional wisdom is that Mr. Sanders faces an uphill battle against more polished politicians, despite his giving Hillary Clinton a tough battle in 2016. Does that not remind you of Mr. Trump in mid-2015? Mr. Sanders and his coalition, like Mr. Trump, are an asymmetrical threat to their party’s orthodoxy.
This also raises an important question on how the media covers modern presidential elections. As Steven Levitt points out in “Freakonomics,” conventional wisdom is often wrong, because so-called experts use their insider knowledge to serve their own interests. Too often, those interests are clicks and cable news appearances.
Sometimes I feel like I have deja vu when reading the latest dispatches from the presidential campaign trail. Reporters write the same stories, cycle after cycle, about Iowa’s corn farmers, New Hampshire’s quirkiness and South Carolina’s barbecue, while ignoring the fact that American politics have fundamentally shifted. In this age of volatility, candidacies like Mr. Sanders’ and Mr. Trump’s are not unusual, they are now the norm.
I would urge looking at future presidential races through this lens. An outsider who had no real loyalty to the Republicans took over the party, and it could happen again.
Insiders didn’t see the 2016 Donald Trump phenomenon coming because they relied on conventional wisdom and viewed Mr. Trump as “not one of them.” But Mr. Trump intuitively understood the country’s simmering frustration and turned it up to a boil. The boiling hasn’t stopped, and won’t, until the concerns of millions of Americans are heard.
Both parties, and the media covering them, should not forget the valuable lessons of the last few years: Listen, learn and act. Not doing so will mean an even further decrease in their credibility.
• Matt Moore was chairman of the South Carolina Republican Party from 2013-2017.

Please read our comment policy before commenting.