Teddy Roosevelt only came to power because Mckinnely was assassinated. The man hated being Vice-President, at the time it was a place where political careers went to die, he wanted to leave, however, luck was on his side or maybe something a bit more sinister. The Republican's didn't want to nominate a progressive which is why he was handed the role in the first place, but after he succeeded Mckinnely, they weren't going to challenge a sitting President off the same party. All this does is put another face into the liberal-wing of the Republican party who competes with Mckinnely or some other conservative, but ultimately being denied the nomination or handed the Vice-Presidency to keep the progressives at arms length.