The U.S. Congress remains (since the Thornton decision of 1995) without electoral limits. This allows congressmen to stay in the office until they don't get re-elected. However, the longer they are in the office the harder they are to get removed from there. That is because elections are all about advertisement and the more money a congressman has the bigger the chance of him being re-elected.
This would not be a problem until congressmen stop working for the people who elected them and start working for re-election. Lobbying, bribery and internal agreements between congressmen happen so that they affirm their place in congress.
For People, not for money.