My impression is that the first debate of a 3-debate series isn’t very decisive. In my opinion, Mondale won the first debate in 1984, Kerry in 2004, Romney in 2012, and Hillary in 2016, but all lost the election. Bush beat a sighing Gore in 2000’s first debate but didn’t maintain momentum and won by an incredibly narrow margin. I don’t really recall 1988, 1992, or 1996.
I don’t remember much about the 1976 debates, the first since 1960, but Ford’s big gaffe when he confused Poland and Yugoslavia was in the second of three debates.
The most decisive debate was in 1980. Reagan won the single debate of 1980 a few days before the election and won easily. But if there’d been two more debates?
All this suggests that who is perceived as the winner in any one debate is quite contingent.
About tonight’s debate, I hope it turns into a donnybrook over who invented the lightbulb.