Why is Mitt Romney getting little or no bump from his convention?

Perhaps it helps to look back on 1992. Ross Douthat points to the excellent Gallup numbers for Bill Clinton from that year and notes that the “92 Dem convention was a truly historic success” and that “ ‘The Man From Hope’ ” video is still more vivid to me than any convention gimmick since.” Indeed, that video was almost certainly the best-ever of the genre; his speech was first-rate; and the stagecraft in general was well-done throughout the event.

And yet, that’s almost certainly not why Clinton received a monster convention bump (before the convention he was struggling to avoid being in third place; after, he rarely trailed). As Douthat mentions, the Ross Perot candidacy had a lot to do with it.

Steve Kornacki nails it in reply to Douthat: “perot had drowned clinton out all spring. when convo started, most people still associated him mainly w/ scandal.” Indeed, to really understand the ebb and flow of polling in 1992, you have to go back to January, when Bill Clinton was introduced to the American people in a post-Super Bowl 60 Minutes appearance that was all about scandal. Then, as Kornacki remembers, Clinton never really received a normal spring bump from clinching the nomination, because that was when Perot mania was at its peak.

In other words, regardless of the quality of the convention, Clinton was poised for a large bounce because lots and lots of people who “should” have been Democratic voters in 1992 – weak Democrats, a fair number of pure independents, and perhaps even a decent number of solid Democrats – were not with him when the convention started. And what conventions do well is to convert those “should” voters into solid voters.

That’s why no one expected a big bounce for Romney this time, and that’s why it’s unlikely he would have had one even if the Republicans had put on the best show ever. There just wasn’t very much low-hanging fruit; Romney had basically consolidated the Republican vote by early spring.

So basically, Romney didn’t get a large bounce because he had long ago done most of what the bounce does. Not that Romney had a great convention anyway, but even if he had there just wasn’t much there to get.