Third Party Spoilers
Let it be noted that no third-party candidate anywhere ever cost a major-party candidate an election. Have third-party candidates gotten vote totals that more than cover the spread between the Dem and the Rep? Of course.
But major-party candidates lose elections all on their own. If they cannot close the deal with voters - even with all the institutional advantages they possess - well, that's their problem. Don't blame others for your own failure to woo voters.