Convention Potential: Past poll bounces ranged from -1 to +16 points
U.S. presidential candidates historically have seen a median increase of five percentage points in their support in preference polls among registered voters after their party’s nominating convention. The average is slightly higher, six points, due to the record 16-point increase for Bill Clinton after the 1992 Democratic convention.
The conventions, and their subsequent effects on voter preferences, are an expected and anticipated part of each presidential campaign. Nearly all presidential candidates have seen at least a minimal increase in their support when one compares the last Gallup poll conducted before the convention and the first poll conducted after it. The only exceptions were George McGovern in 1972 and John Kerry in 2004. (See page 2 for complete pre- and post-convention estimates for all candidates.)
Clinton’s 16-point bounce came after he was running third behind Republican George H.W. Bush and independent Ross Perot in polls in the spring and early summer of 1992. Perot dropped out of the race during the Democratic convention, at which Clinton and the Democrats successfully got voters to focus on the poor state of the economy and to blame Bush for it. The 16-point bounce estimate is not a function of Perot’s departure because it is based on a comparison of vote preference questions before and after the convention that asked voters for their preference between Bush and Clinton only.