Congressmen also have access to free internet, which allows them to network, build websites to promote themselves and their ideas, and access to information on bills, background information, and biographical data in a manner not afforded to challengers. When CompuServe tried to level the field by offering free sites to challengers in 1996, the Federal Election Commission shut it down, stating that such a service would qualify as a gift to a candidate.
In presidential contests, the much derided Super PACs have done much more benefit candidates who were not independently wealthy, allowing them to stay in the race for much longer and thus allowing more Americans to have meaningful participation in the process. Is it any wonder so many incumbents want to ban them?
We must remember that those making campaign laws have a direct conflict of interest. They aren’t going to support laws that undermine the supremacy that incumbents enjoy. If anything, they will seek to further it. Where many see money as unfairly shaping our elections, the reality is that the stemming of that money by incumbents who already enjoy incalculable benefits is what really makes the system unfair. Just as politicians have been infamously known to redraw district lines to ensure their reelections, they also redraw the lines of the law in order to handicap their competition. Meaningful change can never come from a system where 90% of congressmen are reelected every time.
References: The Incumbency Advantage in U.S. Elections: An Analysis of State and Federal O±ces, 1942-2000 http://economics.mit.edu/files/1205
Why Incumbents Want Campaign Finance Reform http://www.cato.org/publications/commentary/why-incumbents-want-campaign-finance-reform