The bouncing ball polling theory

I have never really heard this political analogy before.  It comes from John Zogby, in a column by his brother James Zogby over at the Huffington Post:

Even "good news" (like the killing of Abu Musab al-Zarqawi) ormanufactured media events (like the "surprise visit" to Baghdad) don'tprovide dramatic results for the White House. My brother, John Zogby,has long compared Bush's poll ratings to a bouncing ball. Over the pastsix years, each time the President gets a "bounce" in the polls, it issmaller than the one before. Clearly this President is running out ofsteam. While a sitting President can never be discounted, despite staffchanges and other efforts at rehabilitation, the downward pull ofdomestic and international realities are working against the WhiteHouse.

In other words, the later in a presidency you go, barring an unprecedented major event, each political bounce that a president gets becomes smaller each time.  For example, Bush got almost a 40% bounce after 9/11.  He got a 20% bounce when we went to war in Iraq.  He got around a 10% bounce after his address at the Republican convention in 2004.  Following the Iraqi elections, it was about a 5% or 6% bounce, depending on what poll you look at.  Lastly, after the death of Zarqawi, the bounce was about half that (see for yourself).

So, barring a terrorist attack or a military strike on Iran, there is little that Karl Rove can do to change the President's image.  This is where political realism defeats ideological maneuvering.