Some of my leftist friends have declared that if Hillary Clinton is the Democratic nominee (and if their favorite, Bernie Sanders, isn't) they will not support Clinton in the election.
I noted that the Republic Party thanks them for their support.
This has brought the expected charge that there is no difference between the two parties, and that if leftists do not support the Democratic Party that will, somehow, teach the party a lesson.
American politics is structured to be a two-party system. Third parties almost always spoil the chances of the party they are closest to. Not voting for one party helps the other.
Sen. Sanders has said he will not run as a third party candidate. He reads the structure of our system better than some of his socialist followers. I am sure he will support the Democratic nominee.