Ethanol has become a 4 letter world with the Democrats also. Mostly because of how many acres that should not be row cropped have been taken out of CRP (and other programs) and put back into production. Soil erosion has returned, and most of there are not closed watersheds, so all the silt, clays and excess nutrients flow down stream to somewhere else.
So it makes the water purification more expensive to the downstream users, adds to the hypoxia zone in the gulf and degrades a limited natural resource (the soil).