The GOP and Trump are doing what the Koch brothers paid them to do. Many GOP lawmakers signed the “No Climate Tax” pledge, drafted by "Americans for Prosperity" that was funded by the Koch brothers. If a GOP lawmaker shows support for green energy, they would see their campaign money dry up, or a primary challenger arise(1).

(1) https://www.nytimes.com/2017/06/03/us/politics/republican-le...

Jane Meyer (author of Dark Money) also talks about this recently

http://www.newyorker.com/news/news-desk/in-the-withdrawal-fr...