Here’s a not implausible scenario: It’s January 2020. The Iowa caucuses are just one month away. There’s still an unwieldy pack of Democratic candidates, but several have dropped out after realizing that you actually need political talents and a message to run for president. In the home stretch, only four or five Democrats have a real shot to win Iowa or New Hampshire. The candidates and the media are bouncing from town to town, stuffing their bloated campaign-trail bodies into bulky winter coats, dutifully meeting future caucusgoers in cafes and Pizza Ranches. Every reporter is searching hopelessly for an outlet to plug in their phone. After the latest packed campaign event at a brewpub in Waterloo with decent Yelp reviews, political reporters swarm one of the Democratic front-runners for a media avail, eager for a response to Donald Trump’s latest tweet about Don Lemon. Into the scrum steps a mischievous reporter from a troll-y conservative news site. He asks the candidate a cheeky question invented out of thin air: “Senator, Alexandria Ocasio-Cortez just tweeted that the government should add a 10 percent tax on John Deere tractors in an effort to fight carbon emissions from farms and transition into a new hybrid tractor market. What do you think of that?”

Ocasio-Cortez has not said such a thing and likely won’t. But she and her legions of online supporters have become, in a matter of months, the de facto weather vane for progressive sentiment. So what are the chances this Democratic candidate in Iowa, baited by a Breitbart bro with a fake A.O.C. policy proposal, endorses this made-up idea on the spot, in that brewpub in Waterloo? As depressing as it sounds, there’s a small but realistic chance this fiction would actually come to life. Ideas that once seemed out-of-bounds are now creeping into the mainstream of Democratic politics, with social media acting as the accelerant. Democrats, in the rush to appease the noisiest voices on the Internet and grab onto any gust of fleeting attention, so far have shown they’re willing to jump on a bandwagon of ideas that Barack Obama would never have endorsed on his way to winning two presidential elections: backing reparations, abolishing ICE, getting rid of the Electoral College, running away from the word “capitalism.” As The New York Times put it on Tuesday, “activists are leveraging the early stages of the Democratic primary, creating pseudo-litmus tests for candidates eager to respond to the energy that is driving more extreme policy proposals.”

These “extreme” litmus tests get re-tweeted online with emoji claps from activists (and journalists whose reporting often veers into activism). Many of those same people point to polls showing that progressive momentum is on their side: a survey last week from the Des Moines Register showed that “more than half of likely 2020 Democratic caucusgoers [in Iowa] say they would be satisfied with a presidential candidate who wants the U.S. to be more socialist.” Times have certainly changed since Obama ran for office. There’s great hunger among Democrats, from New Hampshire to Arizona, for bold policies designed to empower the middle class and fix a grossly distorted economy in which the richest 1 percent of American families own 40 times the average family’s wealth. Once-forbidden ideas like Medicare-for-All and a wealth tax sound both audacious and common sense. Democrats of vastly different cultural backgrounds, whether they shop at Whole Foods or Piggly Wiggly, seem united in their contempt for unaccountable billionaires and corporations. Even hedge-fund honcho Ray Dalio tweeted a video of himself this week calling the country’s wealth gap “a national emergency.” These are arguments Democrats can win, especially with President Trump proposing almost a trillion dollars in cuts to Medicare over the next decade. Conversations like these are why Bernie Sanders and Elizabeth Warren are at the forefront of the Democratic conversation.

But this Democratic primary is about to test something else: whether burgeoning public support for daring economic policies coincides with support for more hot-burning cultural issues that seem to dominate Twitter in the Trump era. In other words, Democratic voters are very down with Medicare-for-All. But do they want to be talking about reparations or socialism in a head-to-head against Trump next year? Already, at least one prominent Democrat, Ohio Senator Sherrod Brown, is sounding an alarm, however gently, about a presidential primary in which the current rule of the game appears to be chasing the latest shiny metal object on Twitter to win over the most plugged-in and fashionable online.