"I wonder if he's tough enough"
Here's a guy who chose to devote several years of his life working as a community organizer on the tough streets of poor, crime-ridden Chicago neighborhoods. If I know Chicago, its people and its politics, I have no worries about his toughness.
Some people mock him for putting that on his resume, instead of more "impressive" credentials such as high level corporate positions, or Washington gov't work. I would say the experience makes him more in touch, and more attractive, as a leader.