A lot of people are taking note of the fact that Barack Obama has dipped below 50% in the Gallup daily tracking poll for the first time in his Presidency. It is not unusual and in fact expected that Presidents will fall below that magic 50% threshold at some point – Obama’s predecessor spent his entire second term below 50%, for example, and Ronald Reagan dipped below 50% ten months after his election, roughly the same time that Obama has.

What can be said about this milestone, such that it is, is that it’s utterly predictable given the trajectory of joblessness and the economy. Nate Silver provides this chart showing that Obama’s approval ratings and his ratings on the economy has been linked since the first day of his Presidency. The health care ratings are moving in the same direction.

The economy, I suppose, is sort of boring to talk about: it’s a slow-moving sort of thing, and one over which the President has only a certain modicum of control. And so you’ll have pundits attributing Obama’s slide to all various and sundry sorts of things — Health Care! Henry Louis Gates! Torture Trials! — when really it’s just been very much about the number of people who have come to blame Obama about the economy has tended to accelerate faster than perceptions of the economy itself.

Silver recommends that a job creation bill get to the President’s desk, and fast.

A new CNN poll out today shows that Democrats are gradually being blamed more and more for the recession, which stands to reason since they hold every branch of government. And the OECD says that the economy will continue to be sluggish through 2011. “Jobs, jobs, jobs” should be the main chant in the halls of Congress between now and next November.