The one sobering thought that veteran Republican consultants are already contemplating is that the larger the wave this year, the more difficult it will be to hold onto some of these seats in 2012 and 2014 in the House and 2016 in the Senate. The bigger the wave, the weaker the class and the harder it will be to hold onto those seats. Democrats only have to look at their 2006 and 2008 classes for plenty of examples. What this means is that we will likely have our third wave election in a row this year, and the bigger this one is, the more likely that there will be a countervailing wave in either 2012 or 2014.
Obviously a lot of this hinges on what we make of the concept “wave election.” But let’s just say a “wave” election is one in which one party makes large gains and a “non-wave” election is one in which the net change in seats is small.
In that framework, what I think Cook’s analysis misses is that the current Democratic majority is very large. Consequently, for the GOP to obtain even a small majority would require a “wave” of wins. But if they get a “wave” and a small majority, there’s nothing about “small GOP majority” that should lead us to expect a future wave. It’s only if Republicans win a gigantic net gain of 70-75 seats that would leave them in the position of holding many Democratic-leaning districts.