Three weeks ago today, Democrats were heading toward an electoral disaster. Donald Trump had his largest lead, with polls showing him within reach of winning New Jersey of all places. Trump was ascendant coming off an assassination attempt and a largely successful convention. The Democratic Party was divided and despondent.

In three weeks, everything has changed in ways that were impossible to imagine the moment Joe Biden announced he would step aside. This is now a complete toss-up with all of the momentum and energy on the side of Kamala Harris and Tim Walz. It’s the most stunning and rapid reversal I have seen in my political career.

1. Harris Immediately United the Party

One argument against Biden stepping aside was the concern that replacing him could lead to a dangerously divisive process. Some even likened it to the chaotic 1968 Democratic Convention. However, this comparison overlooked the true sources of division within the party. The more likely scenario was the party rallying together to defeat Trump, much like it did in 2020 when Biden unexpectedly secured the nomination.

However, it wasn’t just party elites and elected officials who coalesced around Harris. The voters did, too. The simplest explanation for Trump’s polling lead over the last year is that Trump had consolidated his 2020 voters and Biden hadn’t. In the New York Times/Sienna polling, Trump typically got the support of 5% of people who said they voted for him in 2020, and Biden was only getting around 87%. This gap came from Biden’s low approval ratings, concerns about his age, and the fact that even before the debate, 40-50% of Democratic voters said they preferred a different nominee.

Well, Kamala Harris solved that problem...