His most crucial appointment, though, will be his choice for Treasury Secretary. Some Obama insiders say this decision has already been made - and there is speculation outside the camp that it could be Larry Summers, Bill Clinton's former Treasury Secretary, or Timothy Geithner, the chairman of the New York Fed. Other names include Paul Volcker, the 81-year-old former Fed chairman, and Jon Corzine, a former Goldman Sachs chief who is now governor of New Jersey.