It doesnt make any sense why she lets Candy interact with her at all

If she truly despises the guy and wants to beat him,
she wouldn't let him feel he had the freedom to call her
up whenever he felt like it to rattle her.

She should not be interacting with him at all (or at least
wait until after the election is over). Every time he calls
her, he's inflicting some insult or insinuation upon her,
and she's not getting anything in return: no information
about his campaign; she's not getting in his head; nothing.

She knows what he's doing ("trying to get in her head") but
she lets him do it anyway.

And the character Billy Bob Thornton is giving is a truly vile
character. There's nothing redeeming about this guy, nothing
attractive. The audience has nothing but loathing for the guy.
Thornton just chose to put nothing at all attractive in this
character. He's an unambiguous negative. That line about how
he's "going to masturbate for hours to her?" I mean: WTF?
So, why does she even talk with him? If she just told him
"GTF away from me" when he approaches, that would not be displaying
weakness. That would just be displaying common sense.

For her to interact with him, its almost like she wants to punish
herself, she wants to fail, she wants to lose the campaign to him.
And, while there is some self-destructiveness to her character
(her alcoholism, her past depression) that would seem to be behind
her now, no? She -does- want to win this campaign, doesn't she?