I'm pretty sure that "vote for me or admit you're racist" is not necessarily a fallacy. It seems reasonable to conclude that through rather straightforward logic.
Assumption 1. If you are not a racist then you should not support racist policies.
Assumption 2. The opposition wants to enact racist policies while I do not.
Proposition 3. From 2, if you vote for my opposition then you are supporting racist policies.
Theorem 4. Therefore, from 3 and 1, if you don't vote for me then you are racist because you are supporting racist policies.
Assumptions 1 and 2 could be incorrect in certain circumstances (in particular assumption 2), but the reasoning is correct.
This argument assumes that supporting racist policies is racist. That may seem tautological, but consider: someone holds a gun to my head and threatens to kill me if I don't vote for the opposition. Am I racist for voting for the opposition?
That may seem extreme, but what if candidate #1 is racist, but candidate #2 has vowed to eliminate funding for medical care I need to live and can't afford on my own? Is voting for #1 racist?
In both cases you’re still racist, assuming the power gradient flows from you to the underprivileged group. You are willing to put your self interest ahead of others. This is ok. You can just say “I’m sorry, self interest demands I be racist”. Germans joined the Nazi party so they could be eligible for good jobs. They say things like this about their grand parents to this day.
If the desire to save one's own life at the expense of an underprivileged group is racist, I'm going to go out on a limb and say nearly everyone is racist.
Assumption 1. If you are not a racist then you should not support racist policies.
Assumption 2. The opposition wants to enact racist policies while I do not.
Proposition 3. From 2, if you vote for my opposition then you are supporting racist policies.
Theorem 4. Therefore, from 3 and 1, if you don't vote for me then you are racist because you are supporting racist policies.
Assumptions 1 and 2 could be incorrect in certain circumstances (in particular assumption 2), but the reasoning is correct.