For those of us old enough to remember the last tragic years of Lyndon Johnson’s administration, the country’s mood offers eerie similarities. Then, as now, overwhelming majorities of Americans agreed that things had gone terribly, incomprehensibly wrong for the most powerful nation on earth, and they demonstrated their displeasure with marches, sit-ins, student strikes, and (in the case of the ’60s) destructive and violent inner-city riots. Confident Republicans naturally blamed the increasingly unpopular Johnson for the sour state of affairs, while his erstwhile Democratic allies quickly forgot about his once-heralded legislative triumphs in their worries over a seemingly endless war and frightening domestic unrest. In Johnson’s case, his historic success in passing long-stalled items on the Democratic agenda (Medicare, major civil-rights bills) looked increasingly irrelevant in the midst of ongoing national agony, just as Obama’s achievements in passing health-care reform and financial regulation have done nothing to alleviate fears of national decline and looming disaster…

Beyond such oddly assorted long shots, one potential challenger counts as Barack Obama’s worst nightmare and, according to my off-the-record conversations with some left-of-center activists and theorists, is currently considering making history with a radical presidential run as either a Democrat or an independent.

Of course, to challenge an incumbent president of your own party, it helps if you’re at least a little bit insane. By this standard, Gene McCarthy probably qualified. And Al Gore—yes, Al Gore—certainly does.