People have forgotten about this because we all hate him now but a major dynamic in the PA-Sen race was people who were concerned about Fetterman’s facilities but way more personally repelled to the point of negative polarization by the attacks on him
Plus we also thought the Republican is a phony self-serving assh()le who didn't represent us at all...a smarmy carpetbagger who was simply unacceptable. Didn't matter that the Dem was recovering from a bad stroke, we just shrugged off his debate problems.
He's tacked towards the center, and with regards to Israel, he's probably closer with the center-right. This has alienated a lot of his more outspoken left-wing supporters and staff.
There was another further left primary opponent in the race (Kenyatta) but he was third, behind a more traditional center left candidate (Lamb). Fetterman was seen as a blue collar progressive.