There have been some well known Dems who eventually became climate skeptics.

<< Recall Michael Shellenberger who was Time Magazine's Hero of the Environment is one example.  An active writer and lecturer these days.

<< The founder of Gaia environmental theory, James Lovelock, switched to the skeptical side.

<< Recall the Canadian scientist, Dr. Patrick Moore who was a co-founder of Green Peace,  quitting that group and then became a writer & lecturer for the skeptics.

<< And then there's the former Sierra Club president and EPA scientist, Dr. Alan Carlin, who wrote opinions differing from his EPA colleagues, the warmist advocates.  For several years Carlin wrote his monthly blog about the science supporting the skeptical view. 

And there has been more who joined the skeptical side of these discussions.

So there's some hope.