From Gallup:
Gallup’s most recent trial heat of presidential preferences, from a Jan. 29-Feb. 1 poll, shows President George W. Bush trailing Massachusetts senator and Democratic front-runner John Kerry by a 53% to 46% margin among likely voters. A review of historical trial-heat data from past elections shows it is rare for an incumbent president to be trailing at this stage in a campaign. At the same time, in the eight elections analyzed here, there have been campaigns in which the incumbent led in February but was defeated for re-election in November. As such, it is hard to draw any inferences as to what Bush’s current standing means for his re-election prospects.
Gallup has a long history of asking presidential trial-heat questions in election years. There are comparable data from as far back as 1948 for elections in which an incumbent president was pitted against his eventual challenger in January or February of the election year. While it is not clear at this point who the Democratic nominee will be, Gallup’s historical polling shows it is rare for an incumbent to be trailing any named opponent at this early stage in the election year. The only other time an incumbent trailed his eventual challenger (or, for that matter, any other possible opponent tested) at this stage in the campaign was in 1976, when Democrat Jimmy Carter held a slight edge over incumbent Gerald Ford, 48% to 46%. (Carter eventually defeated Ford in a close election.)