Predicting the Convention Bounce

How much of a bump can Barack Obama expect from the convention? TPM Election Central reports that a McCain campaign memo is pushing the expectation that Obama will get a whopping 15 percent boost in the polls in the aftermath of next week's convention. The memo uses Bill Clinton's big 16 point bounce in 1992 as the benchmark, a problematic comparison considering that Ross Perot dropped out of the race at the end of the convention. Nate Silver of FiveThirtyEight.com, writing in New York magazine, calculates the average convention bump to be six points. That feels about right to me, given the relative stability of polling results over the last several months. The McCain campaign memo tries to discount in advance Obama's power as a speaker, even noting that the speech will come on the anniversary of Martin Luther King's "I have a dream" speech. This is a little like saying Michael Phelps is likely to swim really fast. You can raise the expectations, but that didn't stop him from blowing his rivals out of the water. Likewise, Obama is till going to have millions of Americans tuning in as he delivers what should be another spellbinding performance. And if more people tune in for Obama than for McCain, the impact of his speech will be accentuated. The Pew Research Center just published some polling that shows greater interest in the Democratic convention than the Republican convention. Across the board, Democrats, independents and Republicans said they are more interested in following the Democratic convention by about ten percentage points. Interest in the Democratic convention is running 23 points higher than in 2004. With more voters tuning in, Obama will have a greater chance to turn voter his way than will McCain the following week.