But leading Democrats understand that it offered the best hope — until Sanders. His supporters claim that times have changed. They point to the popularity of some of his proposed programs, President Barack Obama’s reelection after declaring his support for gay marriage, and polling showing that Sanders does better against Trump in head-to-head matchups than some of his opponents. But, it’s worth remembering that before Bush’s campaign unloaded on Dukakis, he led the vice president by 17 points. That’s germane, because President Trump’s lack of popularity means that to win he will need to make his opponent even less likable — Bush’s predicament in 1988. Sanders’ background as a self-proclaimed democratic socialist and history of controversial statements will be easy fodder.

There is also more recent evidence that being perceived as too far left is still problematic: in 2018, Democrats conducted an unintentional experiment in Arizona, one of 2020’s few swing states. Senator Kyrsten Sinema ran as a moderate, and won by 2.4 percent, the first time that a Democrat won a Senate race in the state since 1988. By contrast, gubernatorial candidate David Garcia ran as an unabashed progressive, and lost by more than 14 points, albeit to an incumbent governor. Across the country, many of the candidates trumpeted by the left, including those who triumphed over more moderate opponents in Democratic primaries, lost their races, including several in winnable districts. Just last week, a new poll revealed that while 45 percent of Americans say they would vote for a socialist for president, 53 percent would not. And Republicans see Sanders as such a liability that they are already trying to tie down-ballot Democrats to him.