IOWA CITY, Iowa — Democratic voters say that more than anything, they want to beat President Donald Trump in 2020. But some worry that means putting their hope of electing the first woman president on hold. "I can hardly think about it. It makes me sick thinking about how nasty this could get for a woman,” Marianne Mason said, clutching her stomach as she waited for Sen. Kamala Harris of California to arrive at a town hall event at the University of Iowa on a recent Wednesday night. "How are they supposed to rebut someone like Trump? I want to...