WASHINGTON (Reuters) - Former New York mayor Michael Bloomberg’s charity gave another $64 million to a campaign that aims to slash the number of U.S. coal-fired plants by two thirds by 2020, he said on Wednesday.

FILE PHOTO - Former Mayor of New York City Michael Bloomberg speaks during the "China and the U.S.: One Belt, One Road and 100-Day Plan," a discussion hosting high-level delegation of Chinese leaders, in Manhattan, New York, U.S., June 14, 2017. REUTERS/Bria Webb

Bloomberg Philanthropies made the donation to the Beyond Coal campaign run by non-profit Sierra Club, and other organizations fighting the burning of coal. Including this latest donation, the charity has given $110 million to Beyond Coal since 2011.

The pledge was made a day after President Donald Trump’s environmental regulator announced a move to scrap former president Barack Obama’s Clean Power Plan that would have reduced carbon emissions from coal plants.

The Trump administration labeled the Clean Power Plan part of a “war on coal” by Obama.

But Bloomberg said that since the plan has been tied up by the courts and never came into effect, the real threat to coal comes from competing power sources, such as cheap natural gas, solar, and wind power, as well as communities, local governments and companies concerned about public health.

“These are the groups that are fighting the war on coal and it’s happening all across America and they are winning,” Bloomberg said at an event at the Sierra Club in Washington.

Since 2011 nearly half of the country’s coal-fired power plants, or nearly 260 plants, have been closed.

Beyond Coal wants to push communities to fight coal plants which emit carbon and particulates blamed for lung and heart problems. It aims to increase closures to some two-thirds of the U.S. coal fleet by 2020.

While domestic coal use is under pressure, coal exports have risen this year amid high global demand. The Energy Information Administration, the independent statistics arm of the Department of Energy, said on Wednesday that U.S. coal exports were up 62 percent from January to July, compared to the same period in 2016.

But U.S. coal-fired power plant closures have continued apace since Trump came to office in January. Last week, Luminant, a subsidiary of Vistra Energy Corp, said it would shut its Monticello plant in Texas next year, joining about 10 other plants that have announced their closure since Trump came to office.