Koster was recently recorded saying he doesn't support abortion in cases of rape, and twice used the phrase "the rape thing."
Democrat Suzan Delbene's spokesperson Sandeep Kaushik calls Koster's comments "callous," and says he treats rape as if it's nothing more than a political issue.
Koster's campaign declined to comment, but issued a statement calling the secret recording a "vicious and desperate" tactic, and saying "he very clearly and honestly stated his thoughts on an extremely sensitive subject," and "he has nothing to be ashamed of here."
