A Naturally-Occurring Experiment on the Electoral Impact of President Biden’s Decision to Exit the 2024 Presidential Race

We assess the impact of former President Joe Biden’s unprecedented decision to exit the 2024 Presidential race 2 months before election day by analyzing a naturally-occurring experiment surrounding the incumbent President’s decision to exit the 2024 race, a period in which we fielded the second wave (N_{Wave 2} = 831) of a nationally-representative panel study (N_{Wave 1} = 1400), with random invitation assignment (from the original response pool) throughout Wave 2. Pre-registered difference-in-difference (DID) analyses reveal no evidence of significant turnout or down-ballot effects across either the US adult population or partisan subgroups. However, post hoc tests reveal substantial gains in excitement about the 2024 campaign across both the general population and (especially) among self-identified Democrats after President Biden’s decision to drop out. Elevated excitement coincided with (a) increased belief in core democratic principles and (b) increased donation to Democrats up and down the ballot.