The storm is already pulling politics out of shape, changing the dynamic of the last few days before the election.
The crowd had gathered in the open air, beneath a huge stars-and-stripes and giant white letters reading: Vote Now.
This was to have been an important, high-energy moment on the first day of the last full week of campaigning. But the double act was robbed of its star attraction.
The president had arrived the night before and moved the event earlier but, even so, he decided he had to return to the White House as the other big speaker, former President Bill Clinton, explained to the crowd.
"I was supposed to be the warm-up man - but that storm had other ideas," he said.
He said they had stayed up late planning the rally and talking but, this morning: "He called me and he said: 'I gotta go back, it's going to be worse than we thought. It's going to hit further south of where we thought,' so keep your fingers crossed for your fellow Americans today".
The event had far less energy than if the president was here but it is proof that politics will not stop in the vital swing states away from the storm.
Mitt Romney too has cancelled events planned for tonight and tomorrow.
His campaign said it was "out of sensitivity for the millions of Americans in the path of Hurricane Sandy", adding "Governor Romney believes this is a time for the nation and its leaders to come together to focus on those Americans who are in harm's way".
But there is a risk that he is shoved out of the picture.
The media are not interested in the candidates' speeches, even if they still make them.
But, more than that, it puts the spotlight on President Obama as a leader in a time of crisis - both in terms of deeds and words.
This is exactly what politics, what being a president, is really all about and, in a country haunted by the spectre of Hurricane Katrina, this is a moment of huge importance for the president.
One of great opportunity and, if he fails to rise to the occasion, of great peril.