How grimdark do you want to get with basically President Daniel Plainview?
Based on his OTL attitudes, he would probably enact most of the early New Deal reforms and toy with authoritarianism far more than FDR ever did. Race relations will probably be worse than OTL, and he would almost certainly chime in with the Hitler chorus during the early stages of the Nazi takeover, noting the effects that "strong rule" can have on economic recovery.
If he feels the public's about to turn on him, he might even go so far as to engineer a fake Business Plot (read: Reichstag Fire) and put the country under martial law like his propensity to break out the State National Guard during his time as Governor.
But it all really depends on how much like "It Couldn't Happen Here" you want to make this unfortunate USA.