It's not enough, apparently, that some of the wealthiest Americans spend millions to elect their candidates to Congress. Now they are using their fortunes to lobby Congress against any limits on their ability to buy elections. Koch Companies Public Sector, part of the industrial group owned by a well-known pair of conservative brothers, has hired a big-name firm to lobby Congress on campaign-finance issues, according to a registration form filed a few weeks ago. The form doesn't say what those issues are, but there are several bills in the House that would reduce the role of anonymous big money in campaigns, and restrict the kinds of super PACs and nonprofit groups that the Koch brothers and others have inflated with cash. Clearly, it's vital to the Kochs and others like them to prevent such limits from being enacted; their network raised $400 million in 2012, and it has been extremely active again this year. To that end, they have done something ordinary citizens cannot do: They hired the lobbying firm of a well-known former senator, Don Nickles, Republican of Oklahoma, to press their interests. Mr. Nickles started his firm a few months after leaving the Senate in 2005, and he takes in up to $8 million a year from big firms like Exxon Mobil, General Motors and Walmart. This is a perfect illustration of the cumulative power of cash in today's Washington. Members of Congress get elected with substantial help from check writers like the Kochs and others. Once there, they do the bidding of former members paid by the Kochs to preserve their business interests and fight off campaign-finance reforms.