Andrew Egger: “We don’t know yet whether Kamala Harris and company will ride out of this week with the traditional post-convention polling surge—after all, parties don’t usually ride into their conventions on the heels of a race-resetting, vibe-unleashing change to the top of the ticket.” “But here’s what we can say: Two days in, the Democrats are undoubtedly putting on the kind of high-energy, focused, and above all unified show that good polling tends to follow.”