Given the current makeup of the executive branch, it’s not hard to imagine a scenario where Secretary of State Mike Pompeo might, with the help of an aggressive attorney general, Bill Barr, challenge any attempt by Nancy Pelosi to ascend to the presidency if both Trump and Pence are incapacitated by Covid-19—perhaps even preemptively putting out a legal opinion that Pompeo is the legal next in line for the acting presidency.
Could Nancy Pelosi assume the acting presidency and fire Bill Barr to get her own contrary legal opinion? Would Bill Barr treat such an order as legitimate? Would the Supreme Court weigh in? How those questions would be answered would almost certainly hinge less on actual legal fights and more vague public sentiments—questions like whether the president or vice president looks likely to recover.
“The nation could thus be deeply divided, in a hard-to-resolve way, on the very basic question: Who is the (acting) president of the United States?” legal scholars Jack Goldsmith and Ben Miller-Gootnick wrote back in March at the beginning of the Covid-19 pandemic.