Which explains why, 22 weeks before Iowa hosts the lead-off caucuses, most of Biden’s rivals are not forlorn. Elizabeth Warren is positioning herself — through an impressive political machine with few peers — to possibly win both Iowa and New Hampshire. Bernie Sanders knows the history, too; he and Warren both hail from states that border New Hampshire, and voters there have never passed on a chance to back a New Englander. In South Carolina, where six-in-10 Democratic primary voters are expected to be black, contenders like Kamala Harris, Cory Booker and Julián Castro see potential. And then there’s Pete Buttigieg, whose fundraising shows little sign of limitations; 300 people on payroll, including 70 in Iowa and 50 in New Hampshire.

In other words, the Labor Day campaign launch of the frenzied fall push comes at a moment of tremendous peril for Biden, potential for his rivals and promise for Democrats who, above all else, want to beat Trump. First, though, they have to settle among themselves who will get the chance to do so. And, at the moment, it is possible to see paths for most of the mainstream hopefuls.

Biden remains the most plausible candidate, having built up chits over decades in politics dating back to his first election in 1970. But the last week has left some aides more worried than ever.