Booman is right. A third party run for president by Trump would all but guarantee that the Democrats (i.e. most likely Hillary Clinton) would win the presidency, but would hurt Democrats on all the other contests on the ballot.
Because I think Democrats are already heavily favored to win the White House again (although this is by no means a guarantee), a third party run by Trump would be a net loss for the Democrats. Without a 3rd party Trump run, the Democrats have a good shot at winning both the Presidency and the Senate. With a 3rd party Trump run, they will win the Presidency and probably remain a minority in the Senate, plus, the state races will get another injection of crazy rightwing office holders. In my mind, it's just not worth it.
Because I think Democrats are already heavily favored to win the White House again (although this is by no means a guarantee), a third party run by Trump would be a net loss for the Democrats. Without a 3rd party Trump run, the Democrats have a good shot at winning both the Presidency and the Senate. With a 3rd party Trump run, they will win the Presidency and probably remain a minority in the Senate, plus, the state races will get another injection of crazy rightwing office holders. In my mind, it's just not worth it.
