Since the Democratic National Convention, Obama’s approval rating in the Gallup tracker increased from 44 to 50 percent. Who propelled Obama's bounce? Check out the chart below:

If nothing else, the DNC solidified the support of Obama leaning voters. Obama’s largest gains came among Hispanics, independents, non-white voters, moderate Democrats, and high school educated voters. In contrast, seniors, Republicans, and conservatives barely budged in Obama’s direction, if at all. Predictably, liberal Democrats and postgraduates held relatively firm as well, perhaps since Obama had already maximized his gains among those core constituencies. On balance, this suggests the DNC acted generally consolidated Obama’s existing coalition rather than persuade genuine converts.

It's important to recall that Gallup's approval tracker is of all adults, not just registered voters. And the Gallup head-to-head and approval trackers have occasionally disagreed as a result. For instance, they’ve routinely found Obama outperforming his approval rating among non-white voters in match-up with Romney and it’s impossible to say whether that’s due to a mass of unregistered non-white voters who don’t approve of Obama’s performance or a large number of registered non-white voters who aren’t voting for Romney but harbor real reservations about the presidents performance. After the DNC, the gap between Obama’s standing in the horse race and his approval rating among non-white voters vanished. Even if that doesn't reflect genuine gains, Obama's now on firmer ground with the Latino voters essential to his chances in states like Nevada and Florida. Along those same lines, gains among high school educated, somewhat religious, moderate white voters will also help Obama in those two states as well. 

Since many of Obama’s gains seem concentrated among Obama-leaning voters, they seem somewhat more likely to endure. Non-white voters and moderate Democrats might have even already supported Obama against Romney or were likely to move in that direction--the DNC was just the impetus for their return to the Democratic fold. Other gains—like those among pure independents—might prove ephemeral. But the fact that a large number of “pure independents” were willing to shift in Obama’s direction demonstrates that undecided voters won't necessarily break overwhelmingly toward Romney.

The fact that Obama's gains didn't come from Republican-leaning groups is also a reason why Romney might struggle to make a big comeback. On twitter, some have observed that Kerry reduced Bush's lead from 6 or 7 to 2 or 3 points by election day. If Romney could make a similar comeback, the argument goes, he would be positioned for victory. The issue, however, is that Bush's 6 or 7 point lead was bolstered by a large number of previous Kerry voters moving to the undecided column following the RNC. Eight years ago today, Bush led Kerry 49.2 to 43.5 for Kerry, compared to Kerry's 48 percent following the DNC. And Kerry wasn't just beneath his post-convention peak, Kerry held more than 43.5 percent of the vote for most of the summer. After Kerry performed well in the first debate, many of these voters returned to his side. 

Unlike Bush, Obama's lead isn't artificially inflated by Romney voters hanging out in the undecided column . Today, Romney holds 45.5 percent of the popular vote, compared to a post-RNC peak of 46.8 percent. Unlike Kerry, Romney's 45.5 percent is actually above where he spent most of the summer. Realistically, Romney will eventually return to around 47 percent of the vote in September, but he hasn't demonstrated an ability to advance far beyond a pretty stable base of voters who disapprove of Obama's performance. In contrast, Obama stands just shy of 49 percent, placing him within striking distance of reelection after a DNC that consolidated the Democratic base.