Do political parties save strong candidates for specific elections?

Great Debates
1

Hypothesis: In 1991, President Bush’s approval rating was extremely high, and he looked like the logical winner of the 1992 election. It seems possible that the Democratic Party had written off the 1992 election, and looked to the 1996 election to realistically take back the White House. If this is true, then the DNC didn’t nominate their best candidate, rather “saving” him for the '96.

This is similar to 1996, when President Clinton was the presumptive favorite, and the RNC nominated Bob Dole, and “saved” GW Bush for the 2000 election, when Clinton couldn’t run again, and the Republicans would have a better chance.

My questions are:

  1. Does this hypothesis have any validity? Do the two major parties “save” their best candidate for an election which has no incumbant running, or do they always, in every election, nominate their best candidate.
  2. If this hypothesis is true, who were the Democrats “saving” in 1992? Had GHW Bush been reelected in 1992, who would have been the Democratic candidate in 1996? And, back when GW Bush had much higher approval ratings and looked like a lock for this Fall’s election, who were the Democrats “saving” for 2008? Hillary Clinton? Someone else?
2

I don’t know that its so much a conscious decision by the party as a whole, as it is by the candidates. Running for president takes up a lot of time, money and effort, and if you lose, you’re forever tarred as the guy who ran for president and lost. So, a candidate might decide not to run if he’s convinced that he couldn’t win. In 1992, for example, Mario Cuomo, who would have been a strong candidate, decided not to run because he figured Bush was too strong to beat.