John McCain is America's favorite kind of candidate. With his record of extraordinary patriotism and his distinctive Senate tenure, McCain is a nominee whom voters from both parties — and independents, too — could easily support. But he has been dealt a terrible hand: a tanking economy, an unpopular war, a Republican incumbent whose approval ratings are at their all-time low and a gloomy national mood, with 82 percent of Americans saying in a Washington Post-ABC News poll last week that the country is on the wrong track. Political scientists add all that up and predict that the Democrats are...