I’m still advising caution on interpreting the effects of the conventions. We know Mitt Romney didn’t get much of a bounce if any, and we know that Barack Obama did get one — but until we see that Obama bounce recede, we won’t know if anything has changed overall.

However, Obama’s bounce has done something important: it means that he continues to shadow the approval ratings of George W. Bush in 2004, when he won reelection despite public dissatisfaction with key aspects of his performance.

Here are the numbers from Gallup. Obama (2012) caught Bush (2004) at the end of April of this year; of course, Bush had been well ahead of Obama as he spent 2002 and 2003 working off the effects of the rally effects from September 11th and the Iraq invasion. By spring 2004, however, he had fallen just below 50 percent approval. Then, over the summer, Bush generally tracked a point or two better than Obama has.

The last Gallup poll before Bush’s convention had him at 49 percent. The convention boosted him to 52 percent approval, and he rallied a bit more to peak at 54 percent in late September before falling back to around 50 percent for the remainder of the campaign.

Obama entered his convention a bit lower, in the mid-40s. However, he spiked up (in Gallup’s three-day polling) to a high so far of 52 percent, and has now drifted down to 50 in yesterday’s reading. That’s not an isolated finding; the Washington Post/ABC poll has him one point lower, at 49. We’ll have to see whether he will rapidly return to sub-50, or if his bump will prove longer-lived, as Bush’s did.

The general conclusion, however, is that Obama continues to closely track only just a bit behind Bush in 2004. As Greg noted yesterday, this is nothing at all like 1980, when Jimmy Carter couldn’t even reach 40 percent approval. It’s also nothing like, say, 1996, when Bill Clinton was safely over 50 percent from March 1996 through the election.

Which, again, points us in the direction of a very, very, close race. But it’s possible that we’ll see something in the next couple of weeks that changes that, and it’s possible that Mitt Romney is a weaker challenger than John Kerry and that therefore Obama has a bit more of a cushion than even Bush did eight years ago.