My dad is almost one of the the people FlyingSquid talking about; he’s a Democrat and kind of racist, but he doesn’t see himself as a racist. Someone like a more Republican version of my dad might be persuaded to vote for Harris, or at least not vote for Trump, if the Trump campaign gets too nasty.
Don’t forget that magats aren’t the only people who would potentially vote for Trump; a lot of people are swing voters who, for some reason, have a hard time deciding who to vote for. Neither candidate can win without appealing to a majority of those voters.