Get caught on tape saying sexist, racist, or generally offensive comments to a large portion of the population. Oh wait, never mind.
Actively collaborate with a foreign government against the interest of the USA. Oh wait, never mind.
Enrich himself and family at the expense of the USA. Oh wait, never mind.
Engage in outright nepotism. Oh wait, never mind.
Actively obstruct justice. Oh wait, never mind.
Put kids in cages. Oh wait, never mind.
Enact policies and force a government shut down that craters the economy due to his ego. Oh wait, never mind.
Support white nationalist publicly and enact other overtly racist policies. Oh wait, never mind.
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At this point if any and all of the above doesn't change their minds, I don't think we should have delusions that policies could be so offensive to turn his base.