If you expand atheist to include "nonreligious" or agnostic, then I think that it's just a matter of time 'til we have such a nominee.
In the US identifying as an atheist aside from simply "none" is seen as a political statement and basically the same as "new atheism", for example even Kyrsten Sinema doesn't identify as an atheist, she simply describes herself as "non-religious". So very low.
This. Few nonreligious people call themselves atheists because that term is more aggressive & comes laden with baggage.
