Nationalization started massively under Roosevelt in the 1930's.
Luckily back then the Congress and Supreme Court used a little thing called 'The US Constitution' to shut down most of the more outrageous grabs at power. But nowadays they don't let that sort of thing stop them.
Remember that it's the Congress that is responsible for raising taxes, writing/signing bills, and all that happy stuff. Obama or Bush have actually very little to say about the matter other then just getting public opinion to put pressure on Congress. The USA president is more of a easy scapegoat (or figurehead, depending on current public mood) then any effective force. They have virtually no power to affect the economy or write bills or do anything of that nature on their own. The President office is suppose to be more concerned about things like the military or international matters then anything else.