The worlds biggest oil and gas companies were major financial supporters of the Clinton Foundation last year, according to a National Journal report.

Also contributing to the Clinton Foundation was a major Canadian trade agency pushing for approval of the Keystone XL pipeline.

According to publicly available records, ExxonMobil, Anadarko Petroleum, and the Foreign Affairs, Trade, and Development Canada agency all opened up their checkbooks for the Clintons' charitable organization last year. ExxonMobil has donated between $1 million and $5 million to the foundation, which works with individuals, nonprofits, and the private sector to advance a range of charitable causes. The Canadian foreign affairs, trade, and development agency donated between $250,000 and $500,000. Anadarko, one of the world's largest oil and gas companies, donated between $50,000 and $100,000. The Canadian trade agency lists strengthening ties with the United States, an aim it suggests could be achieved by building the Keystone XL pipeline, as one of its top priorities, according to the agency's website. And the CEOs of ExxonMobil and Anadarko have publicly urged the president to green-light the pipeline, which would haul heavy crude from Canada to the Gulf Coast. […] BP, ConocoPhillips, Chesapeake Energy, CITGO Petroleum, and Occidental Petroleum have also each donated between $10,000 and $25,000 to the foundation. In addition, Dow Chemical, a chemicals manufacturer that has also backed construction of Keystone, contributed to the foundation last year, donating between $1 million and $5 million.

Hillary Clinton has thus far refused to take a stand on the Keystone XL pipeline.

Her foundation holds that no donations are given to win favor from Clinton, saying "the Clinton Foundation is a philanthropy, period."

Environmental groups that oppose the Keystone XL pipeline are not convinced. They are growing frustrated with Clinton's ties to the oil industry and her refusal to take their side on environmental issues.