What would the consensus be then?
In May 1978, would Carter be "unbeatable" despite a tough 1978 midterm? Would Ronald Reagan be considered a Ted Cruz equivalent?
Carter would've been the favorite (there's a tendency to bet on the incumbent) but not unbeatable. I think even in late '77, from stuff I've seen/read, he was considered a possible one-termer. Reagan was not a Cruz equivalent; he was taken very seriously after '76.
In May 1990, would anyone who said Bush was very vulnerable be laughed out of the park?
Probably. I thought he was potentially vulnerable because of the economy/political cycles.
In May 1983, after the bruising '82 midterms, would anyone really say that Reagan was on his way to a 49-state landslide?
No.
I guess you're really talking about who was most likely next president in the year of the midterms?
2010 - Obama.
2006 - This is difficult. Partly because I wasn't here back then so I don't know what people were saying. I never took Giuliani seriously at all, so it's always surprising to read claims he was a favorite. And this early, people thought
Bill Frist and
George Allen were GOP frontrunners. McCain I didn't think could win the nomination. I thought Hillary would have trouble too; I probably would have bet on Gore or Edwards (Obama was not a factor yet). Mark Warner was also in the mix, especially on boards like this. I think "the Democrats" were already favorites by May '06 (Bush was pretty unpopular) but McCain probably lead individually.
2002 - Bush
1998 - Gore. May '98 was smack in the middle of Lewinskygate - Gore could have been the incumbent by 2000.
1994 - Clinton. The House was still considered "safe" until fall. There's the incumbency, Clinton's charisma, the economy starting to recover, and Dole (the GOP frontrunner) being a dud candidate, though some thought he was formidable.
1990 - Bush.
1986 - Bush was not considered a strong candidate. There was an awareness of how bad veeps had done historically. I think it would've been close between him and Gary Hart.
1982 - Again, close between Reagan (incumbent) and either Kennedy or Mondale. This board would have preferred Reuben Askew.
1978 - Carter. I think there was already some talk of Kennedy by then, though.
1974 - Kennedy (notice a pattern?), maybe Scoop Jackson.
1970 - Nixon. Kennedy had just been through Chappaquiddick, and I don't think Muskie became frontrunner until later.
1966 - LBJ, from what I understand, was a pretty heavy favorite until the '68 NH primary. Given the '64 landslide, RFK was probably considered more likely than any Republican. Rockefeller after that.
1962 - JFK obviously.
1958 - Nixon, but not heavily. In reading about the '60 election, I was surprised to learn that JFK was already considered quasi-frontrunner (among Democrats) in '58, and lead Nixon in some polls.
