In my non-humble opinion, my Differential Equations class bordered on the useless. DiffieQ has a few very valuable lessons to learn, but they are buried in a whole lot of cruft that has little value, both from a theory perspective and from a practical perspective.
One of its useful results is that certain types of systems with a certain critical amount of negative feedback inevitably result in oscillations, no matter how you try to avoid it. This pops up all the time in the real world, but extends beyond the obvious physics applications.
(Recall that "negative feedback" is not a value judgment; it means that when the system goes in a certain direction, a force will begin to act more strongly in the opposite direction. Positive feedback means the opposite. A ball on the top of a hill is experiencing positive feedback; whichever way it goes, gravity will continue to pull it. A ball in a hole is experiencing negative feedback; no matter which way it goes, it will be pulled back into the hole.)
Press coverage has several negative feedback cycles; the one of interest today is that as anything becomes generally approved, there is always negative feedback caused by the human nature's fundamental impulse to be contrary. We inevitably see cycles in coverage.
Tom Maguire has a "bold prediction" that there will be an Obama backlash. I don't see this as a "bold prediction"; I see it as the only possible course. It always happens that way. No matter how biased the press may or may not be, nobody can sustain a continuous positive presence in the media. (Continuous negative presence typically manifests as simply dropping off the radar after a while; there is a threshold there.)
The other interesting result from diffieQ is that you can put a mathematical basis behind "the bigger they are, the harder they fall"; the larger the positive amplitude, the larger the negative amplitude you can look forward to.
There are caveats and exceptions to all of this; one could profitably study these phenomena for a lifetime. The less connected it is to any sort of real news, the more it oscillates. (I think the exceptions of constant news that you might be reaching for your keyboard to cite at me fall under this category.) Political campaigns are in practice conducted in a vacuum, in that while the campaign is important, they are not currently actually connected to the real world, so inconsequential things like "tearing up at a press conference" are blown into massive stories because there's so little actual signal the press needs to crank the amplifier up to 11 to maintain its constant coverage levels*. This further encourages oscillations.
There will be Obama backlash, then Obama backlash backlash. The question is how it will all play out in the votes, not whether there's going to by cyclic coverage.
(I think that a savvy political manipulator could learn to manipulate these cycles, but it would be a challenge.)
It is also worth pointing out that the cycles are getting faster, thanks to new media. This is the longest presidential campaign ever in more than one way; not only is it the longest according to the calendar, it is also experiencing the fastest news cycles ever. So, in terms of news cycles, this campaign is probably easily twice as long as the 2004 campaign. And it's only going to be worse in 2009 when the 2012 race starts...
*: Which itself is a problem; the news must always be at the same high intensity, continuously. If that means covering a disaster, great! Otherwise, if we have to pump up a minor political snafu or some celebrity's drug arrest, will do! This has the same deadening effect that a compressor has on music. But... how can CNN say "Hey, it's a slow news day, we're going to run an hour of classical music"?