This is the map with all Roosevelt votes added into the Taft column. 50.6-41.8 victory in the popular vote and 379-152 in the electoral college. Is this plausible? I think that Taft definitely still would've won re-election in 1912, which would change the course of history, but by a much slimmer margin. Many progressives would've stayed home, and I could see a ~5 point victory.
I disagree. While to a lesser extent, Wilson was also running on an outspoken Progressive platform.
Even without TR's candidacy, his dissapointment in Taft was well known and many of his supporters simply wouldn't stomach voting for the incumnent. At best, Taft would have won a narrow victory, nothing close to a comfortable lead.