Who could play that role initially? Some are touting former Indiana senator and governor Evan Bayh, but he's untested and not particularly articulate. A far better bet is newly elected California governor Jerry Brown -- a kind of Eugene McCarthy-esque figure -- who once bragged that he was going to move left and right at the same time. He is, of course, a serial presidential candidate, having run three times previously (1976, 1980, 1992). Though he failed each time, he twice ran impressively, finishing third in '76 after entering late in the process, winning (or having friendly delegates do so) in Maryland, California, Nevada, New Jersey, and Rhode Island. In 1992, on a financial shoestring, he finished second -- winning Maine, Connecticut, Colorado, Nevada, Vermont, and Alaska, while losing California to Bill Clinton, 48-41 percent.

For Brown, the next nine months are critical, as he'll attempt to use his visibility as governor of the nation's most populous state to become a kind of Democratic Chris Christie, standing up to special interests and proposing bold new fiscal policies. If he does, he could be a formidable 2012 challenger, as he's shown a propensity in the past for running on populist themes (term limits, campaign-finance reform), while taking positions that could attract labor support (he was anti-NAFTA) and even backing from conservatives (he has supported a flat tax). As a Catholic, he does have some appeal to the working-class "Hillary Democrats" -- a part of the reason why he's done well in New England in the past.

Could he beat Obama? It's obviously a long shot. But the hope among some is that his entry into the race would so weaken Obama that Clinton might consider getting in, as Robert Kennedy once did, able to tap into a family-built organization in a matter of days. Some even harbor hopes that, under pressure from his own party, Obama might walk away from the job after one term. Stranger things have happened.