In October the head-to-head polls are better predictors of the final vote than are approval ratings. Nevertheless, I've been keeping my eye on the approval scores, and Barack Obama hit a minor milestone today

In Gallup’s latest sounding, Obama’s approval rating hit 53 percent. That’s among all adults, not registered or likely voters.

For some time, I've been watching the comparison between Obama ’12 and George W. Bush ’04; Bush's peak October approval score that year was 51 percent, earned twice over Oct. 14-16 and 22-24.

The key here is that recent presidents who were easily reelected, including Richard Nixon, Ronald Reagan, and Bill Clinton, had solidly stronger approval ratings than has Obama, while his rating is far better than those posted by solidly defeated Jimmy Carter and George W. Bush. In other words, approval scores are an excellent starting point for determining which kind of election to expect, and we’re getting the kind of close, uncertain rate that a president right around 50 percent should have.

Now, some caveats are in order. Obama will get 31 bites of the apple this month, since Gallup has a three-day rolling tracking poll; in 2004, Gallup released on six polls. Obama probably benefits right now from some random variation, and Bush didn’t have a chance to do that in October 2004. Also, Gallup is only one poll; overall, HuffPollster has his approval rating at 49 percent.

It’s also true, as Eric McGhee tweets, that the electorate was better for Bush than Gallup’s approval universe of all adults, while the electorate will be worse for Obama. In that sense, Obama may need to run a bit ahead of Bush in approval rating in order to do as well as Bush in the national vote — although, since Bush won by better than 2 percentage points, Obama doesn’t have to match him in order to take a national-vote plurality.

One other thing to note from the approval ratings is that there doesn’t appear to have been any significant drop in Obama’s approval (in either Gallup or the polling averages) associated with his early October post-debate slump in the head-to-head polls. For today at least, Obama is just about back to his post-convention high.

Again, if you want a specific prediction, approval isn’t going to get it for you. But if you want a reminder about the basic structure of the race, approval is perhaps the best single statistic to explain why this contest remains a close one, with the president a slight favorite for reelection. Presidential approval, and all the things that go into it, are the fundamental conditions driving the contest.