As I remember the race in 1980, the polls from the last weekend mostly showed Reagan with a slight lead. What was captured in those polls was the late-deciders breaking heavily toward Reagan. IIRC, it was late Sunday evening when Pat Caddell told President Carter that there was no way that he was going to win reelection on Tuesday because some key battleground states had slipped out of their reach.
Remember being in line with a bunch of military in Harker Heights, TX who could not wait to vote FOR Regan over Carter. Line was at least 2 hrs long Harker Heights is next to Ft Hood.