Unlike FDR, Mr. Obama will not have to create the mechanisms government uses to interfere with the economy before imposing his policies. FDR had to get the Supreme Court to overturn a century's worth of precedents limiting the power of government before he could use the Constitution's commerce clause, among other things, to increase government control of the economy. Mr. Obama will have no such problem.
FDR also had to create agencies to implement regulations. Today, the Securities and Exchange Commission and the National Labor Relations Board (both created in the 1930s) as well as the Environmental Protection Agency and others created later are in place. Increasing their power will be easier than creating them from scratch.
Even before the current crisis, there was a great demand for increased government regulation to limit global warming. That gives the next president a ready-made box in which to place more regulation, and a legion of supports eager for it.
But if the coming wave of new regulation from an Obama administration is harmful to the economy, Mr. Obama will take a page from FDR's playbook. He'll blame Republicans for having caused the market crash in the first place, and so escape blame for the consequences of his policies. It worked for FDR and, so far in this campaign, blaming Republicans and George W. Bush has worked for Mr. Obama.