The Republican Jewish Coalition has joined the chorus calling on Pennsylvania’s far-right Republican gubernatorial candidate to stop promoting his campaign on Gab, a social media network favored by extremists. Doug Mastriano has 38,000 followers on Gab, a self-proclaimed “free speech” platform that hosts content prohibited on more mainstream sites. It grew in popularity after Twitter and other networks cracked down on extremists in recent years. Mastriano has also reportedly paid for “campaign consulting,” which makes new Gab users automatically follow him. Gab is well known as a hospitable place for antisemitic, racist, and anti-LGBT+ content. Gab’s founder, Andrew Torba, left...