The thing about Taft is that he cant win barring FDR doing something stupid.
Also Willikie said he'd vote for FDR over an isolationist republican, so nominating Taft would drive away many somewhat Willikie minded republicans.
Scenario A - Roosevelt goes full on as an interventionist, pushes for maxium aid to Britain, urges sanctions against Germany, and perhaps makes a publicized trip to Britain to meet with Churchill. The American people like Roosevelt, byt they don't want war, so they dont vote for Taft, they vote against Roosevelt.
Scenario B - Roosevelt says "no 3rd term for me." The Dems nominate Garner and William Bankhead. The GOP nominates Taft/Charles McNary. Perhaps Henry Wallace runs as 3rd party, and draws just enough states away to give Taft a narrow vicory.
I will try to post an electoral map sometine today.
Wishing you well, his majesty,
The Scandinavian Emperor