Biden vs. Trump: Unfit
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Biden vs. Trump: Too old
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The two septigenarians are about equal on the "too old" front.
Biden vs. Trump: Dementia
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Dementia is a more promising line of attack for Trump to use against Biden.
Biden vs. Trump: Health Problems
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Biden vs. Trump: Mental Problems
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Criminal, ethical and moral issue searches
Biden vs. Trump: Liar
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Biden vs. Trump: Corruption
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Biden vs. Trump: Rape
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Biden vs. Trump: Sexual Assault
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The rape and sexual assault lines of attack worked against Biden as Tara Reade rolled out her salacious accusations against Joe Biden which culminated in an accusation of digital penitration. The searches related to Biden petered out when Reade's credibility was vetted. Bringing up anything to do with inappropriate sex hurts Trump more than Biden. Trump himself has steered clear of the topic.
Biden vs. Trump: Racist
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Biden's name was connected to the term "racist" mostly after his "you ain't Black" interview with Charlamagne Tha God. But Trump trumped him quickly in that category with his not so empathetic reaction to George Floyd's death and the subsequent protests.