Something like a policy proposal costing a low but non-zero amount of money for exactly zero benefit outside of the eyes of the 10% who really care about their pet cause. The non-packaged proposals get voted down not because the majority hates them, but because they don't care, at least not like the special interest does.

If a vector space is more your jam, imagine a six-dimensional vector space of policies, and each of these six hypothetical interest groups as voting for any combination of policies with a positive value along the axis in question, and against any combination of policies with a negative value. [100, -1, -1, -1, -1, -1], [-1, 100, -1, -1, -1, -1], etc, will each get voted down when presented individually as policies, but their sum as a package gets supported by each interest group.