I don't know if I understand the question enough to give an opinion, but many of the European countries are ahead of the U.S. in taking climate change more seriously and reducing fossil fuel use. I can only assume the politics are different there.
From what I can tell this early it looks like the dems will be running on a platform of medicare for all and to a lessor degree, the new green deal. Or at least a more active approach to climate change. As much as I like both of these, I'm not seeing this as a strategy to beat Trump's apparently strong economy. It seems like he's missing an opportunity to promote what Americans seem to treasure the most, their wallet. Assuming he is still president in 2020.