THE ART OF THE LEGISLATIVE DEAL: Here is an explanation of how the compromise involved in passing the National Voter Registration Act of 1993 was itself compromised. The Democrats wanted a law that would allow easy registration. The Republicans wanted a law that would require states to keep their voting rolls clean and up to date. They both thought they had gotten what they asked for. But a deal like that unravels when the Department of Justices works a lot harder to enforce one part of the deal than it does the other.

Nobody likes to be a chump.  Unraveled deals have the effect of making future legislative deals harder to make. Legislatures become ineffective.