To support a party by denigrating another is childish and unconstructive. It is the debate of the playground, and rarely rises above the IQ of a Dodo.
Criticise their policies, and or their actions constructively. If you think they made an ass of something, suggest a better way of doing it. If the party you support makes mistakes, criticise it as harshly as you do their opponents.
To say you hate someone, or what they stand for is childish, and requires no thought.
I have often liked someone, only to later loathe them, and vice versa, but I NEVER use the hate word, it's used too casually today.