In his book “Private Empire,” author Steve Coll relates a telling remark that reflects how Lee Raymond, then ExxonMobil CEO, viewed his company’s relationship with America. He was asked whether ExxonMobil would build more refineries inside the United States to help insulate the nation against gasoline shortages.

Raymond: “Why would I do that?”

An oil industry executive: “Because the United States needs it … for security.”

Raymond: “I’m not a U.S. company and I don’t make decisions based on what’s good for the U.S.”

Yet ExxonMobil invests heavily in American politics. U.S. tax law, however, prevents the electorate from knowing the exact nature of that investment — how much money, given to whom or what, and with what intent. That should change, but Congress adamantly stands in the way of such disclosure.

ExxonMobil rates a “heavy hitter” designation from the Center for Responsive Politics, a nonpartisan organization that tracks campaign donations and lobbying expenditures. ExxonMobil’s disclosed campaign contributions in the 2012 cycle exceed $1.2 million. It charted more than $12.7 million in disclosed lobbying expenses in 2011.

It is difficult, however, to determine how much money the corporation gave to the U.S. Chamber of Commerce — which plans to spend more than $50 million this year on political ads supporting conservative issue advocacy. Because the chamber is a non-profit organization, it can shield its donors — and the amounts they give — from the public. This condition will remain until Congress passes the DISCLOSE Act — the Democracy Is Strengthened by Casting Light On Spending in Elections Act.

ExxonMobil may have its headquarters in the United States. Its top executives may be Americans. But it is a global corporation, and its business decisions — and thus political choices — are not necessarily made in the best interests of the United States. So why should its political giving to those superPACs that support tax and regulatory policies that minimize constraints on corporations be allowed to remain secret?

Multiply this by the Fortune 500. Just look at the top 10. Following ExxonMobil are Wal-Mart Stores, Chevron, ConocoPhillips, General Motors, General Electric, Berkshire Hathaway, Fannie Mae, Ford Motor Co., and Hewlett-Packard. Do their economic interests align wholly with those of the U.S. government?

Raymond’s economically rational attitude is hardly confined to strategic planning at ExxonMobil. Other global corporations, even if headquartered in the United States and run by American executives, are not always likely to have the same policy interests as the American government. In a capitalist universe, corporate decisions ought to be in line with the interests of shareholders and not necessarily a nation-state. But why do we continue to permit their financial participation in U.S. politics to remain largely secret?

Also, how many of the Fortune 500 are more than a century old? Many global corporations, such as oil companies facing reserve replacement issues or companies in need of raw materials such as rare earth minerals, have decades-long planning windows. Compared with those, U.S. government policy-making windows are ephemeral. Yet enduring multinationals take advantage of U.S. tax law to secretly influence those fleeting quadrennial moments. They continue to seek tax law and regulatory policy changes that redound to global corporations’ continuing economic advantage.

A month ago, the Senate failed to break a Republican filibuster, curtailing debate on the DISCLOSE Act.

As a result, the American electorate will continue to not know how much money global corporations that do not consider themselves U.S. companies pour secretly into American politics. Corporations are not nationalists, but they’re shoveling undisclosed money into a nationalistic endeavor — electing a government.

If you’re unhappy with that, yell at your member of Congress. Demand Congress pass the DISCLOSE Act. But it’s unlikely your voice will match the influence of massive corporate money you’ll likely never know about — because Congress has become a wholly owned subsidiary of multinational corporations.