Anyone that disagrees with the church being more progressive.
I think there is a false dichotomy – perhaps enhanced by election politics – between red and blue, conservative and progressive.
What about “green”? It seems to me that all people would want to live in a healthy, life-hospitable environment, whether they be “conservative” or “progressive.” I was pretty much reared a conservative Republican, but from an early age was also concerned about environmental issues, harm to God’s great creation. It didn’t used to be that conservative meant being anti-environment, falling in lock-step with big corp pollution and lies about environmental issues. In fact, Nixon and Teddy Roosevelt (both conservatives) are considered the best environmental presidents in the US.
Now that we have come to a new phase in environmental issues and life on planet earth is being threatened by environmental problems, from local to global, and esp future generations, anyone who cares about life and future generations should be concerned and mitigating the problems when feasible, and calling for others to do so.
The Pope is aware of the harms to people in very poor nations, their inability to get pollution-free potable water, the climate changing and harming their agriculture, etc. He is more aware than people living in wealthy, climate-controlled places. He really does care about people and life, so naturally he would be concerned about the lack of concern in some wealthy nations and their participation in perpetrating the harms, perhaps unwittingly.
He has been trying to inform people and reach out with speeches, messages, and encyclicals, but the “hard-line” refuses to listen. That is a serious concern.
The “hard-line” are those who don’t care enough to reduce their harms to others; they may be concerned about other people having abortions, but that seems to be the extent of their concern about life. That’s what “hard-line” means to me. Plus those who tend to lack sympathy for the suffering, maybe because they are too concerned and focused on their own well-being.