Sequestration and the need for emergent parties
The blame game only makes sense in a two party political culture. Negative politics works because no matter how many people you alienate, you win if you can take the other down. But if there were another party, your taking the other party down just gives an opening to the third party. And this is probably how the Green Party will win, there will be a situation where the Democrat and Republican take each other out and the Green Party candidate will be the only one left standing.
Which brings us to sequestration, this would not be happening if the Green Party was a credible threat. Because the Democrats would realize they are just discrediting themselves and creating a space for an emergent party.