GOP volunteers on the Peninsula were manning the phones Thursday night, urging voters across the country to support Donald Trump.
At Hillary Clinton headquarters in San Francisco, Democrats were calling and texting voters.
And at the University of San Francisco, voters crowded into discussion about presidential election.
USF law school Dean John Trasvina, speaking at a presidential roundtable Thursday, contends volunteers at the phone banks are not wasting time, saying the presidential race is so close, mobilizing voters matters.
"In this election, making sure all supporters vote is going to be critical," he said. "It will mean the margin of victory."
With her decades-long political career, it's a challenge Clinton has much more experience with. She also has the widespread backing from her party leaders, while many high-ranking Republicans have declined to help Trump rally the base.
That, however, doesn't mean Clinton is a shoo-in.
"We'll know Tuesday or maybe Wednesday," Trasvina says. "It's gonna be that close; every vote counts."