Sometimes I wonder if the Republican Establishment has learned anything. Why can't some of them accept the fact that for all intents and purposes that Donald Trump is going to be the Republican candidate in the November General Election? Forget the Third Party option. Historically all third party candidates do is drain votes from the party's nominee.
It has been said that a vote against Trump is a vote for Hillary. This may not be accurate as I strongly suspect that the Independent who is running as a Democrat in the primaries is currently measuring his support for an independent run. If Bernie Sanders does run as an Independent that will be devastating to the Clinton Campaign. It will not necessarily benefit Trump, however. A split like that on the Democratic side will likely discourage voters from turning out to support trump thinking that there could be no way Trump could lose. Clinton or Sanders could technically win by default because their supporters would turn out in droves, possibly winning a few states that Trump may otherwise win.
Republicans that are unsatisfied with Trump should give up the Third Party talk and hope to God that Sanders does not enter as an Independent. I would hate to see a situation in which (and this scenario, as improbable as it is, is not impossible) no one gets enough electoral votes for a win, sending the outcome to The House of Representatives for President and to the Senate for Vice President. What happens in this scenario: Trump gets 17 states, Clinton get 17, states, and Sanders gets 16 states? We would have a constitutional crisis since the House is constitutionally required to vote by state. No one would have a majority. Article 2 of the Constitution does not state how to resolve a tie between the candidates. Do we really want to risk that?