Very seriously do or don’t.
If you see no meaningful difference between the position the country and the world is in with a President Trump or Cruz vs a President Clinton then you should not bother voting for the office, or should vote for someone else out of some perceived principle that you possess.
I strongly suspect we will win without you. And we cannot win as a tent that only allows those who pass your ideological purity test to enter. If Obama’s progress and progressiveness and Supreme nominations and overall performance have been such weak sauce to you that you might as well have had Romney or McCain, then, yes, you might be better off in another party more to your liking. Bye.