Yeah, I like the guy .... but, could be wrong, but from this distance it appears he sort of (intentionally?) made Woodrow Wilson President by siphoning off votes, regardless an unmitigated disaster in so many ways still being felt profoundly today.
You are right about TR’s ‘Progressive Party’ run in 1912.
TR knew that by running Progressive he would likely help to elect Wilson, but his desire for revenge got the better of him (after the GOP stole the nomination from him via back-room machinations at the Convention).
Primaries were few back then, and non-binding. In those primaries, he got half a million more votes than President Taft. I’d say he had a legitimate beef.
The problem: The GOP promised him the 1916 nomination if he didn’t run third party. For the sake of the nation he should have shelved his ego and not run.
That third party run was the SINGLE WORST thing TR did in his entire life (for the reasons you alluded to above). And I speak as a life-long admirer of TR. Heck, when I was younger I read about half of the 20+ volumes that he left us on all sorts of topics.
Still, TR’s reply to the “olive branch” from the GOP after he lost the nomination is one of my all-time favorite TR quotes:
“A homily on honesty, given by a thief who refuses to return that which he has stolen, does not lead to edification.”