Whereas Trump supporters see this as a weakness, Biden supporters are spinning it as a strength. “I think that Joe Biden was a bit surprised by the question, but I do believe that Kamala Harris demonstrated that she is willing to take the fight to the opponent,” James Clyburn, the South Carolina Democrat whose endorsement boosted Biden’s candidacy across the South, told reporters on Tuesday. “That question is a furtherance of what makes Biden respect her so much.” Clyburn pointed to Justice Brett Kavanaugh’s Supreme Court confirmation hearings as another example of Harris showing her character. Harris’s camp might also point to the confirmation hearings for Attorneys General Jeff Sessions and William Barr as times when she has not shied away from confrontation but run toward it—a helpful skill as she prepares to debate Vice President Mike Pence this fall.

Biden’s selection of Harris may also signal that he is willing to be challenged himself, Christina Greer, an associate professor of political science at Fordham University, told me. “That he still chose the same woman who critiqued him as his closest partner to rebuild American democracy speaks very highly about how Joe Biden views female leadership and the ability for someone to call him to the mat,” she said. He will “get back up, shake hands, and be willing to listen and learn.”

Progressives hope that, just as Biden signaled he’s willing to be pushed by Harris on race, perhaps he will be willing to be pushed on other issues.