For some reason, I don't think Portman can help in states outside of Ohio. He just doesn't have the stature, especially amongst southern evangelicals. Romney def needs to win Virginia and Portman isn't going to help with evangelicals there who are skeptical of mormonism. Of course, Romney appeals to the moderate-liberal types in NoVa as well, but they won't be a reliable voting bloc. I just think Thune or Burr are far stronger choices, and can win more swing voters and swing states.
Would Thune accept a place on a ticket that looks like it'll lose considering he's eying 2016?
Poll
