The 2008 election may prove to be a test of an old question: How much do individual candidates matter in determining who gets elected president? At this point, the underlying economic circumstances and trends in party identification favor the Democrats, but John McCain has gained in the polls and enjoys higher favorability ratings than either Barack Obama or Hillary Clinton.

The economic models predict a Democratic victory. In a Bloomberg article today, Alison Fitzgerald writes:

Recessions shaped four presidential elections in the past half-century -- in 1960, 1976, 1980 and 1992. Each time, the candidate from the party trying to retake the White House won. A model that uses economic data to predict presidential race outcomes has the Democrats getting 52 percent of the votes cast for the two major party candidates, says Ray Fair, the Yale University professor who developed it.

The economy may be a factor in the shifting balance of party identification among the electorate. This past week, based on 5,566 interviews during the first two months of 2008, the Pew Research Center reported that Democrats enjoy a significant advantage, with 36 percent of registered voters identified as Democrats and only 27 percent as Republicans. The Republican share has dropped by six points in the past four years and represents "the lowest percentage of self-identified Republican voters in 16 years of polling by the Center." What is especially striking is the change in swing states:

Four years ago there were about as many Democrats (35%) as Republicans (33%) in the 12 states where the voting was closest in 2004, and the balance was similar in the 2000 election cycle. But so far in 2008, Democrats hold a substantial 38% to 27% identification advantage in these states.

Looks good for Democrats. But McCain's image may enable him to avoid the burden that Republicans would normally carry into the election. And Clinton and Obama each carry burdens of their own that have no historical precedent and that models based on past elections can't possibly incorporate.

Given the trends, this ought to be a good Democratic year. But for months (and even more strongly in recent weeks), my sense has been that the presidential race is at best a toss-up. Just as in 2000 the Republicans benefited from the misperception of their candidate (who campaigned that year as a "compassionate conservative"), so they seem likely again to benefit from public misperception of their candidate as a moderate centrist, when on the crucial issues of the day--the war and the economy--McCain's positions are indistinguishable from the incumbent president who's got a 30 percent approval rating. It's going to be the Democratic candidate's job to make that clear.