David French of National Review Online considers the impact of social media on the race for the Democratic presidential nomination.

Certainly the Democratic mainstream has become more liberal, and its left-most cohorts are white, female, college-educated, and young. In other words, I just described many of the key demographics of American Twitter — the platform that exercises a wildly disproportionate influence on politicians, journalists, and political activists. The dominant feedback loop in the early primary isn’t just from the motivated base (which would be entirely normal), but a motivated base amplified by a specific social-media platform.

Yes, radical Democratic pronouncements will earn them a wave of negative media attention on Fox News and in conservative media, but not a single Democratic candidate is trying to win that demographic. Indeed, a wave of Fox News hate is good for the brand. But if a Democratic candidate breaks in even small ways from the emerging online orthodoxy, watch them trend on Twitter. Watch them get viciously dragged in real time in front of every single leading progressive politician, activist, and journalist in the United States. It takes a brave person to withstand the attack, especially when there is precious little short-term advantage in confronting the online Left.

This immediate, public, toxic, and often vicious or scornful feedback amplifies existing primary-season pressures to move leftward — just as the same kind of immediate toxic reaction can cow conservatives who oppose Trump. These attacks aren’t just read by campaign staffers. They also provide fodder for journalists, and they can quickly create narratives that dog candidates for days or weeks.