Last month I reported
an update to my research Incumbent Rule. Through an examination of 451 final pre-election polls in campaigns with an incumbent from 1976 until today, 72% of all undecideds broke toward the challenger while 28% of all undecideds broke toward the incumbent. From 1992-2004, that percentage had dropped slightly. Over 283 polls, 66% of the undecideds broke for the challenger while 34% broke for the incumbent.
However, these figures are the average of a wide variety of congressional, gubernatorial and Senatorial races. Even in these campaigns, while fairly well known, the incumbents rarely suffered from 100% name recognition and widespread crystallization of opinion. When looking at only final pre-election polls in the ultimate incumbent versus challenger campaigns--Presidential campaigns--the percentage of undecideds to break for the challenger increases sharply. In 28 final pre-election polls in Presidential elections featuring an incumbent from 1976-1996, a whopping 86% of undecideds broke for the challenger, while only 14% went for the incumbent.
In Presidential campaigns, everyone not only knows who the incumbent is, everyone has a long-standing, well-developed opinion on the incumbent. As
Guy Molyneux shows in the American prospect, incumbent Presidents finish almost precisely where their final poll results project they will finish:
There have been four incumbent presidential elections in the past quarter-century. If we take an average of the final surveys conducted by the three major networks and their partners, we find that in three of these the incumbent fell short of or merely matched his final poll number, while exceeding it only once, and then by just a single point (Ronald Reagan). On average, the incumbent comes in half a point below his final poll result.
Year Incumbent Final Poll % Actual Vote %
1996 Clinton 51 49
1992 Bush 37 37
1984 Reagan 58 59
1980 Carter 42 41
The numbers for challengers look quite different. In every case, the challenger(s) -- I include Ross Perot in 1992 and 1996 -- exceed their final poll result by at least 2 points, and the average gain is 4 points. In 1980, Ronald Reagan received 51 percent, fully 6 percentage points above his final poll results.
Looking at just Gallup,
Mystery Pollster delivers even more bad news for incumbent Presidents:
[T]he final Gallup projections (sans undecided) show an intriguing pattern: In the presidential elections since 1956 that featured an incumbent, Gallup's final projection of the incumbent's vote exceeded the incumbent's actual vote six of eight times. The only exceptions were Ronald Reagan in 1984 and George H.W. Bush in 1992, and then by only 0.2% and 0.7% respectively. On average, Gallup's projection of the incumbent's vote has averaged 1.3 percentage points greater than the actual result. Obviously, without seeing the raw results we can only speculate, but this pattern suggests that Gallup has allocated too many of the undecided over the years to incumbents.
It is quite clear that incumbent Presidents receive very few undecideds from the final polls until the final result. Considering this, Molyneux offers one way to track the Presidential race:
Think of it this way: The percentage that Bush receives in polls represents his ceiling of support; he may get a little less, but won't get more. In contrast, Kerry's percentage represents his floor, and he will almost certainly do better on election day. Assuming that Ralph Nader and other minor candidates will receive about 2 percent -- which is what current surveys suggest -- 49 percent becomes the critical line of demarcation in this election. If Bush can get to 50 percent or above in the polls, he should be able to win. At 49 percent -- where he is today -- we're probably looking at another photo finish, lots of recounts, and narrow state-by-state victories dictating the Electoral College outcome. And below 49 percent, Bush is almost certain to lose.
On the day before the election, if Bush is behind Kerry 49-46 like he was in the recent Newsweek poll, he would be in dire straights indeed.
