Alpha Natural Resources, one of the largest coal companies in America, was a player in major congressional election efforts last year — but you won’t find records of their corporate donations on the Federal Election Commission website or in any public record.

You will, however, find signs of the Virginia-based coal giant’s secret political activities buried in a creditor document filed last Thursday. The recent downturn in coal prices and high debts forced the company to seek bankruptcy protection earlier this month.

The filing lists organizations with which Alpha Natural Resources had any kind of financial transaction, including recipients of grants, creditors and contractors. The filing does not list amounts given or owed by Alpha Natural Resources. A spokesperson for the firm did not respond to a request for comment.

Alpha Natural Resources gave money to an array of nonprofit entities that are not required to report donor information. These groups were pivotal in helping Republicans maintain control of the House of Representatives and in electing the new GOP majority in the Senate.

The corporation helped fund the Kentucky Opportunity Coalition, a secretive nonprofit group that refused to disclose any donor information during the election last year. The Kentucky Opportunity Coalition was the largest outside campaign entity in the Kentucky senate race, spending over $14 million on television and radio commercials to successfully reelect Sen. Mitch McConnell, R-Ky., in his campaign against Democrat Alison Lundergan Grimes.

Alpha Natural Resources also helped finance campaign entities associated with the Koch brothers campaign network, including Americans for Prosperity, Themis Trust (a campaign data company), and Freedom Partners Chamber of Commerce, a clearinghouse used to fund a range of organizations supporting Republican election efforts. The Institute for Energy Research, an advocacy group founded by Charles Koch that lobbies in support of fossil fuel subsidies and against renewable energy policies, had a financial relationship with Alpha Natural Resources.

The company, with operations in Pennsylvania, West Virginia, Kentucky and Wyoming, had once been viewed as a coal industry powerhouse. In 2011, Alpha Natural Resources borrowed $7.1 billion to purchase Massey Energy after 29 employees were killed in Massey’s Upper Big Branch mine.

The creditor filing reveals a number of other revelations about Alpha Natural Resource’s undisclosed political operation. For instance, the company gave money to the U.S. Chamber of Commerce, a trade association that spent over $35 million during the election last year, largely to benefit GOP candidates. It also donated to Americans Allied for Jobs and Security, a group that spent a small amount supporting Republican candidates during the midterm elections.

The company donated to a number of political groups that favor environmental deregulation on the coal industry, including the Ripon Society, a foundation to support moderate Republicans; the Thomas Jefferson Institute for Public Policy, a conservative think tank in Virginia; and the American Legislative Exchange Council, a nonprofit that works with lobbyists to develop business-friendly template legislation used by state lawmakers. ALEC recently produced template legislation to block states from submitting compliance plans with the EPA’s Clean Power Plan, new regulations designed to combat carbon emissions.

The bankruptcy filing lists “Arthur C Brooks C/O AEI 1150 17th St. NW Washington DC,” which appears to be Arthur Brooks of the American Enterprise Institute, a think tank that has campaigned against the EPA’s new rules governing carbon emissions from coal power plants.

Alpha Natural Resources backed the Heartland Institute, an Illinois-based think tank that aggressively works to counter the belief in climate change. The Heartland Institute, which organizes an annual gathering of climate change deniers, gained notoriety in 2012 for sponsoring billboards comparing those who believe in climate change to the Unabomber Ted Kaczynski and cult leader Charles Manson.

Bankruptcy filings are providing a rare window into the subterranean world of money in politics. Earlier this year, The Intercept used a bankruptcy filing to reveal secret donations to dark money campaign entities and think tanks made by Corinthian Colleges, a for-profit college with a high rate of student defaults. Many of the beneficiaries of Corinthian Colleges’ secret money helped the school beat back regulations governing the $1.4 billion per year in federally backed student loans the company received.

Just days after his reelection victory, made possible with the support of the Kentucky Opportunity Coalition, Sen. McConnell announced that his top priority would be to rein in the EPA’s power to regulate coal companies. Alpha Natural Resources considered the EPA rules a top priority as well.