Fetterman immediately was endorsed by two large unions (steel workers and food service) representing 80000 Pennsylvanians. Within just two days of announcing his candidacy he has received 37000 small dollar donations from all 67 counties in Pennsylvania and all 50 states.
Fetterman was endorsed by Bernie Sanders in all of his election cycles and was one of the only people elected to high office in Pennsylvania to endorse Sanders for president in 2020.
PA dems are awful but he has pretty high popularity here, and surprisingly strong rural support for a dem too. Idk who could mount a real challenge to him in the primary.