You may also want to consider the direct effects of coronavirus, because we are also disadvantaged there. Of Democratic senators older than 70 years of age, 7 are currently in seats where a Republican would appoint their replacement: (Warren 70, Manchin 72, Shaheen and Markey 73, Cardin 76, Sanders 78, Leahy 79).
Whereas on the GOP side, only one senator over 70 holds a seat in a state with a democratic governor: (Roberts, 83).
It is morbid but not at all far-fetched to anticipate how this disadvantage might come into play, as well as with the Supreme Court.