These days, the best thing about being mayor of Washington, D.C., is the nice title. The overwhelmingly Democratic city is in an economic contraction, triggered by the Trump administration’s purges of the federal workforce, and is facing a deep budget deficit of $1.1 billion. The metro area lost 1.7 percent of its jobs last year, the worst showing in the country. Meanwhile, a hostile president and Republican-led Congress are able—and eager—to overrule laws, yank away funds, and deploy troops in the city at whim. Perhaps that is why Muriel Bowser, who has held the job since 2015, announced in November that she would not run again. The bitter contest to succeed her has so far replicated the central ideological struggle within the Democratic Party—between a defiantly left-wing politics and the sedate institutionalism it disdains. The Democratic staffer class who will power the party in the coming years will make up a disproportionate share of the June 16 primary’s voters. The front-runner is Janeese Lewis George, a democratic socialist on the D.C. city council. She is …