First, Trump is lowering the bar for Biden in the debates. That is the opposite of what successful candidates do. Trump should be raising the bar for Biden, talking about what an experienced debater Biden is, having participated in so many debates during his more than four decades as a politician in Washington. If Trump continues to dismiss him as incompetent, all Biden will have to do to win is string together a few coherent sentences.

Second, mocking Biden’s decline is offensive to seniors. In 2016, Trump won seniors by nine points, but today, Trump is losing among seniors by six points in key battleground states. His push to reopen the economy has many older Americans spooked, because they are most vulnerable to the novel coronavirus and least concerned about bringing back jobs quickly since most are retired. Instead of helping win these voters back, making fun of Biden’s mental functions further alienates them. Many struggle with memory problems themselves. And while they may not want someone who can’t remember his potential running mates’ names as commander in chief, they also don’t want a president makes fun of someone’s cognitive struggles.

This is not to suggest that Biden’s mind is off-limits. Quite the opposite, it may prove to be decisive this November.