When the rally was over I checked the news. Reports of the killings at the Tree of Life synagogue in Pittsburgh were coming in. The social media posts of the man arrested in the shootings echoed a lie being peddled by Donald Trump, Fox News and some Republican politicians, which paints a group of bedraggled migrants about a thousand miles away as a dangerous invading horde subsidized by a shadowy puppet master. The gunman’s rampage, believed to be the deadliest anti-Semitic massacre in American history, came on the heels of a bomb campaign against leading Democrats that the police say was carried out by a fanatical Trump supporter, and by what the authorities describe as the racist murder of two African-Americans in their 60s at a Kentucky supermarket.

Right now America is tearing itself apart as an embittered white conservative minority clings to power, terrified at being swamped by a new multiracial polyglot majority. The divide feels especially stark in Georgia, where the midterm election is a battle between Trumpist reaction and the multicultural America whose emergence the right is trying, at all costs, to forestall.

“Any time there is progress made there will always be moments of retrenchment,” Abrams said to me later on Saturday. But, she added, “what I am more excited about is the counterforce that we’re seeing in the number of people running for office who represent a much more forward-looking, progressive vision.”

Abrams’s goal is to put together a coalition of African-American and other minority voters and white liberals. The potential is there; Georgia is less than 53 percent non-Hispanic white. “Georgia is a blue state if everybody votes,” DuBose Porter, chairman of the Democratic Party of Georgia, told me.