I feel like it’s gotta be Sarah Palin. McCain I don’t think was gonna win regardless but it turned McCain’s presidency into a joke. Every candidate gets ridiculed by comedians but Palin’s character was devastated. It was endless, Americans everywhere thought she was stupid. It was a huge misstep and the thought of Palin accidentally becoming President if John McCain died would have been unacceptable to a lot of Americans
I think they felt like they needed someone to energize the Right's base, but all it did was cause McCain to lose the Center, which until that point he was pretty close to getting.