[FreeReign]

So these are the rank and file, back bench representatives, expressing their displeasure with their leadership who blocked this, I assume?

Yup. From the article:

The letter came after a memo was signed by members of the GOP establishment saying that “that state legislators had no authority to ignore certified election results and appoint Pennsylvania’s delegates to the Electoral College themselves.”

[Golden Eagle]

The letter came after a memo was signed by members of the GOP establishment

Thanks. I saw that, but why would the original "memo signed by members of the GOP establishment" carry any more weight than this new "letter from 76 of 141 Republican Representatives" in way this one couldn't just supersede it, but sought an alternative path instead?

I'm guessing the original memo was from the Speaker of the State House, State Senate Majority leader, etc, but it's not clear. If it was the State Speaker, sounds like his job might not be safe now!