If TR had been the nominee in 1912, I postulate Wilson would’ve been defeated by an achingly close margin. How so ? Look at the California returns. Taft was not on the ballot in the general election in the state because TR secured BOTH the Progressive & Republican lines. So the race was a good indicator of what such a showdown would’ve looked like between TR and Wilson with the Socialist Eugene V. Debs performing respectably. As it was, TR won the state by nearly a tie vote, less than 200 votes, each getting 41.8%. Debs took 12% and the Prohibitionist took 3.5%.
I’ve played around with 1912 on Dave Leip’s atlas.
If Wilson had gotten all of Debs vote it I think it would have been hella close. But with Debs in their I think either Taft or TR would have taken it.
The pro-Wilson swings in 1916 are perplexing, many Hughes states were close. I guess he got many of those TR voters.