Upcoming debates will almost certainly feature discussion of Gabbard’s shadowy connections to Syria, and more broadly, of the party’s ambiguous post-Obama foreign policy doctrine. There will be greater pressure to conform to Castro’s argument on decriminalizing border crossings, a position that animates the progressive base but may well alienate moderates and independents. The whispers of Buttigieg’s struggle with black voters will surely intensify, and his opponents are already scheming of ways to use one of his debate responses—“I couldn’t get it done”—against him.

This is to say nothing of the other minefields that await: opposition-research files presented on live television, litmus-test questions on issues such as abortion and guns, not to mention the ideological pressure placed on the field by Bernie Sanders and Elizabeth Warren, neither of whom were seriously tested in the first set of debates but whose ambitious big-government proposals are driving the party’s agenda and putting more moderate candidates in a bind.

As for Biden, regardless of whether his poll numbers plummet or hold steady in the weeks ahead, one thing was obvious in Thursday’s aftermath: blood in the water. You could hear it in the voices of rival campaign officials, whispering of how they knew the frontrunner was fundamentally vulnerable due to his detachment from today’s party. You could see it on the faces of Biden’s own allies, who struggled to defend his showing.