Yesterday's New York Times Magazine piece by Nate Silver, "Handicapping the 2012 Election," is fun in a crossword-puzzle kind of way, but I think it cheats a little in the way it characterizes Bill Clinton's re-election in 1996.
I agree with SIlver's general thesis, which is that the outcome of a presidential race depends more on macro factors (primarily the state of the national economy) than on campaign tactics or Electoral College strategy. As he writes, "The sophomoric strategist thinks he can slice the American electorate into a million little pieces and make it more than the sum of its parts. The smart one recognizes our common bonds."
But it seems to me that the strongest argument against the idea that the election will be a referendum on the economy is the growing polarization and partisanship in the US over the past couple of decades. The problem is that the last election featuring an incumbent Democratic president can be used to support both arguments -- that it's all about the economy and that it's all about the trench warfare between the Reds and Blues.
But I think it's notable that Clinton failed to win a majority of the vote even in such favorable circumstances. He got 49.2 percent of the vote -- worse than Truman in 1948, Bush I in 1988, Bush II in 2004, and Eisenhower in 1956, even though their parties held on to the White House in worse economic conditions. And in 1996, a far-above-the-norm 10 percent of the electorate voted for minor-party candidates (mostly Ross Perot, running a second time).
My sense is that Clinton couldn't capitalize very much on the strong economy because there was a huge chunk of the electorate who wouldn't vote for him under any circumstances. By then, the overlap between the two parties (i.e., the presence of conservative Democrats and liberal Republicans) had almost disappeared, and voter "stickiness" (allegiance to one party) was growing stronger. This would also explain why Al Gore got virtually the same percentage in 2000 (48.4) as Clinton did in 1996 despite a weaker economy, and why George W. Bush increased his percentage, slightly, from 47.8 percent to 50.7 percent in 2008 despite a still-weak economy.
I'm not saying that the national economic picture has no effect. It obviously did in 2008, though that year had the worst GDP in Silver's survey and the fourth-lowest performance by an incumbent party. (Stevenson in 1952, Carter in 1980, and Bush I in 1992 all got lower percentages than McCain in 2008.) But it may be weakening a bit as a factor if party loyalty (or antipathy toward the other party) remains strong.
In Silver's chart, change the heading "Electoral college result" to "Popular vote majority," and you'd have to change Clinton in 1996 (plus Truman in 1948) to losses. That would make the case for GDP as predictor look a little wobblier.