Ironically, no faction has done more to stop the expansion of nuclear power than environmemtal groups and green parties.
So environmental groups have done more than most, possibly tied with the military, for nuclear power.
Greenpeace for its part has lobbied hard against nuclear power for decades.
As for regulation, nuclear is governed by a totally separate regulatory structure, that can have its stringency throttled up by anti-nuclear types to prevent new plant approvals.
I can easily name environmentalists who called for more nuclear power. I can even name nuclear PR reps who pretended to be environmentalists (who probably count for this purpose).
Meanwhile, the key benefits of nuclear over coal are various reductions in pollution.
If you dont care about pollution, then there's no reason to not use coal. So Environmentalists win again.