From Opinion Journal's Poltical Diary (link requires subscription):
Somewhere around the 1930s a not so subtle shift began in the character of the typical elected office holder. The growing power of the legislative officeholder and the resulting prospects for personal advancement turned a short-termThat's why I reluctantly support term limits.
altruistic contribution to society into a long-term political career opportunity. Hanging on to a political office gradually became a more important incentive in itself... The twin shocks of the Great Depression and WWII launched an expanded federal, state, and local government involvement in society that went from less than 5% of GDP to something like the current 35%. The power of the elected legislators grew proportionately. The fallout, thus far, has been bad and it is likely to get worse. Since getting re-elected is now a do or die situation for ones political career, the Professional Political Class have tried to stack the election process in favor of incumbents. And they have pretty well succeeded. About 98% of incumbents are re-elected when they stand for office.