How can I pick 0?
Kasich would have been destroyed by now based on his Lehman Brothers involvement when the bank went bust. And he's a spineless RINO, so he wouldn't fight back effectively.
Apparently your definition of "fighting back effectively" is yelling "wrong" when your opponent states facts in a debate, bringing up widely known, 20 year old sex scandals involving your opponent's spouse that no one cares about anymore, and saying that your opponent doesn't "look" like a president.
Trump is polling worse than the "spineless RINOs" McCain and Romney were at this stage too, so all his fighting sure isn't helping him much.