Tonight marks a turning point in the Democratic primary fight. Yes, this is the first head-to-head matchup between Joe Biden and Bernie Sanders. But it’s far more than that: It could be a significant pivot point in the campaign.

In the wake of the coronavirus pandemic, both candidates suddenly have a real-time example to draw a contrast with President Donald Trump and his handling of the crisis. There’s little question that this almost certainly benefits Biden, highlighting his argument that he is ready to govern on Day One.

Not only does he intend to address the coronavirus crisis tonight, he plans to immediately turn “to more of a presidential footing,” in the words of one Biden adviser, and start delivering more speeches “about the gravity of the moment.”

At the same time, the crisis robs Sanders of one of his biggest strengths: His ability to draw massive crowds of supporters – something Biden has always struggled to do. Presidential campaigns often do not end on the same subjects as they begin. The 2008 campaign closed on the economy. It’s still an open question what the 2020 campaign turns on, but tonight is an inflection point – felt different by both campaigns.