Lawmakers of both parties are desperately trying to stop the Internal Revenue Service from interfering with the most powerful political invention that ever fell into their laps: the use of non-profit groups as a source of unlimited and anonymous campaign money. An investigation now unfolding in Utah ... exposes in remarkable detail how profoundly the non-profit system can be corrupted for the benefit of a single industry and a single politician. The politician involved was John Swallow, a former lobbyist for an empire of payday-loan and check-cashing companies. When Mr. Swallow ran for Utah Attorney General as a Republican in 2012, his strategist established several social-welfare groups, which don't have to name their donors, so that the payday-loan industry could support him financially without anyone knowing. The groups collected hundreds of thousands of dollars in secret donations from the industry, and the money was used to run attack ads against Mr. Swallow's opponent, who wanted to crack down on payday lenders. The ads worked, and Mr. Swallow was elected. When the I.R.S. started looking into the non-profit groups and demanding documentation, ... Congressional Republicans accused the agency (falsely) of singling out conservative non-profit groups. Eventually, a parallel state investigation drove Mr. Swallow from office; he resigned last fall, and last week a state legislative panel accused him of breaching the public trust by hanging a veritable 'for sale' sign on the office door that invited moneyed interests to seek special treatment and favors."