Yeah there is no time when it goes off on it's own, it's always in an AU. I wouldn't worry too much about it because the show plays lose in time and skipped a year.
However I swear they talked about Reagan in an episode….
Could've been a continuity gaffe, I suppose. I didn't watch the show that often so I'm not at all qualified to discuss this beyond noting the real world legal ramifications, or lack thereof, of a resignation.