There is a third choice :)
You can always write-in. That's what I'm gonna do if the GOP nominates a RINO.
But that doesn't do anything, write-ins have no chance to win.
Say we are at Pizza Hut deciding on toppings.
Refusing to vote for pepperoni because you would prefer fried catfish is useless.
The catfish isn't on the menu.
You can vote for catfish all you like but you can't get it at Pizza Hut.