The Washington Post describes its latest poll as “virtually unchanged” from the one taken just before the Republican and Democratic national conventions. Among registered voters, in late August, the Post and ABC News found Mitt Romney with a slight lead over President Obama, 47% to 46%. In its post-convention poll, among likely voters, it finds an equally tight race with Obama slightly ahead, at 49% support to Romney’s 48%.
This looks like good evidence if you’re inclined to think that the Democratic convention was a wash for President Obama. But it’s an odd way to make the comparison. Unless there’s no gap between registered voters and likely voters, then it makes more sense to ask two different questions: What was the pre-convention/post-convention change among registered voters, and what was it among likely voters?
The previous Post poll didn’t survey likely voters, but given the usual Republican advantage among likely voters—who tend to be whiter and wealthier than the electorate as a whole—it’s not unreasonable to assume that Obama trailed among those most likely to vote. Subtract a point from Obama’s total, and you’re probably close to his level of support among likely voters before the conventions.
When you compare apples to apples, the Post and ABC News echo Gallup, showing a significant convention bounce for Obama among registered voters. The president makes a four-point gain to 50% support, while Romney loses two points to finish at 44-percent support (which, incidentally, matches the average negative bounce he received from his convention). Of course, this also means that Obama received a bounce among likely voters. It’s hard to know where he stood in the previous poll, but odds are good that he saw a similar-sized bounce of three to four points.
In other words, there’s nothing in the Washington Post survey that challenges the results of other polls. The tracking polls from Rasmussen and Reuters show Obama with a five- point lead among likely voters, and the latest CNN survey has Obama with a six-point lead over Romney with said group, and an even larger lead of eight points among registered voters. According to Nate Cohn at The New Republic, Obama has received an average bounce of 4.6 points from the convention, giving him his highest support since Romney wrapped up the Republican primary in April.
Of course, as Team Obama has pointed out on several occasions, this bounce could prove to be ephemeral—by next week, the race could return to its pre-convention status quo. But it’s also true that conventions are the one time during a campaign where candidates can break out and establish a lead. Ronald Reagan saw his most significant gains following the 1980 convention—and, contrary to a myth Republicans are fond of recalling, maintained that lead throughout the fall—as did Bush in 1988 and Clinton in 1992. This makes sense; the convention is the one time in an election where candidates have a chance to show themselves in the most positive light available. If you can’t convince the public to rally to your side during your convention—even if the gain is fleeting—then odds are good you won’t be able to do so in the fall.
The important takeaway from Obama’s convention bounce isn’t that he’s in the lead; it’s that—in most surveys—he has convinced a majority of the public to support him for reelection. Even if his bump dissipiates, it’s this, more than anything else, that makes him the favorite for November. Romney can still shift things in his favor—the debates are less than a month away—but his chances are dwindling.