As you should know, Phil Ochs was well known for his sociopolitical positions. I don't know how far you want to go with that, but folk-influenced artists who come to mind include Steve Goodman, Arlo Guthrie, Bruce Springsteen in some of his work, John McCutcheon, and Steve Earle. I'll let you evaluate their merits rather than endorsing them myself.

There are noteworthy female artists, too, if you're interested.