What went unnoticed, however, was that Bush worked with Bloomberg as he gave millions to environmental groups to take down the coal industry.
Bush, who's looking to win the Republican presidential nomination, served as a founding director of the Bloomberg Family Foundation -- now called Bloomberg Philanthropies -- from 2010 through 2014. During Bush's second year with the organization, Bloomberg donated $50 million to the Sierra Club's "Beyond Coal" campaign.
The Sierra Club's anti-coal campaign took Bloomberg's money in 2011 to cut coal production 30 percent by 2020 through litigation, lobbying for more environmental regulations and activism. The Beyond Coal campaign has also targeted coal-fired power plants with litigation, most recently forcing the closure of the 200th coal plant in the country.