With all due respect to previous posters, I think we need to look further back in history and consider Andrew Jackson. Jackson singlehandedly destroyed the Bank of the United States, not only by vetoeing its renewal but also by withdrawing funds from the bank to cripple it. He enforced removal of the Cherokee Indians even though the Supreme Court under John Marshall had indicated he had no right to do so. It was not for trivial reasons that he was often ridiculed as "King Andrew the First."
What about Barrack Obama? His moves of government take-over of private industry such as General Motors and Chrysler Corporation and bailing out banks, even firing a bank president are certainly expansions of power. And, appointment of various "czars" that did not have to have congressional approval is clearly an expansion of executive power.
I will also go with GBW and FDR. Each of these Presidents met some incredibly chaotic times that shook the comfort zone of the most powerful nation in the world. This being said, they had to perform duties outside of what is expected of a president: They had to also infuse the country with confidence, safety, and hope. Aside from this, they had also to revisit protocol that had been known to the country and they had to re-build or re-create them almost in their entirety.
This is where the President has the need to expand his boundaries in order to leave room for the many variables that can occur as a result of dramatic social changes.
I think I would have to agree that it is probably between those two mentioned above. I would also have to agree that FDR is probably the one who did the most to expand the power of the presidency. I would say that a lot of what Bush did piggy backed of of the actions of FDR.
It depends upon whether you are referring to pure political power or to the power of the office itself. FDR showed and increased the power of the presidency as he developed policy to move the American public forward after extremely trying times. President Bush increased the political power of the presidency as he moved the country forward after 9/11, but he also was responsible for more governmental control/power with passage of such things as the Patriot ACt.
I think it is a tie between George W. Bush and FDR for the reasons given above. Certainly, I think it can't be ignored that Presidential power definitely expanded under the presidency of George Bush, but whether he was fully responsible for this expansion is debateable. At the same time, FDR played an important role in setting precedents in terms of the use of new presidential powers.
I agree that Presidential power expanded during George W. Bush's time, but I am wary of giving him much of the credit for that. The Patriot Act was certainly not his idea, but that of Republican House leadership (merely a law and order conservative and neo-conservative "wish list" of government powers hastily collected and passed after 9-11). Vice President Cheney was often the man pulling levers behind the curtain, so to speak.
I would actually still give the nod to FDR, since the ways in which he expanded the power of the office served as important precedents. A president can nationalize major industries in an emergency, but FDR was the first to do so. He also used Executive Orders nearly as frequently as Bush's signing statements, but FDR orders had more authority and impact. Every President after FDR, from Eisenhower and LBJ through Reagan and Bush Sr. have used FDR's precedents for some of their own actions.
Wow... good question. I suppose I'll go with George W. Bush. He is not the only "wartime" president to expand executive powers, but he is the most recent and "his" expansions have yet to go away like Lincoln's or Roosevelt's did. So I would argue that Bush has done more to expand the powers of the executive both in its dealings with the people (Patriot Act, wiretapping, etc) and in its relations with Congress (signing statements).