When asked what kept him up at night, Ben Wikler, who is responsible for delivering a must-win state in November as chairman of the Wisconsin Democratic Party, used to answer, “unknown unknowns.” He no longer has to wonder what such a risk might look like. Presidential campaigns, parties and state election officials are scrambling to heed health warnings while safeguarding the democratic process against a growing coronavirus epidemic whose scope is difficult to predict. Their planning has included advising voters not to lick their mail-in ballots, relocating polling places away from senior living communities, and weighing whether to move forward with plans to bring tens of thousands of visitors from around the world to Milwaukee and Charlotte for the planned Democratic and Republican summer conventions, respectively. Former vice president Joe Biden’s digital staff was envisioning options for virtual campaigning if sweeping changes were necessary. Sen. Bernie Sanders’s campaign already has an elaborate streaming operation, which it said it could tap in the event that campaigning is curtailed. Already, both campaigns have been providing hand sanitizer at events. Over the weekend, the AFL-CIO, the nation’s largest federation of unions, canceled a presidential forum scheduled for Thursday in Orlando, where Biden and Sanders (I-Vt.), the leading contenders for the Democratic nomination, had been scheduled to appear. It was the first such cancellation to have been attributed to the coronavirus’s spread.