Waiting for the Republican White Knight

The prevailing assumption about the 2012 GOP primary now seems to be that the race could well come down to a contest between an unelectable wingnut (e.g. Michele Bachmann) and an uninspiring loser-to-be (e.g. Mitt Romney or Tim Pawlenty). So there is a thirst for another candidate to enter the race and save the party from itself. Indiana Gov. Mitch Daniels is on the top of the list, but some are pining for New Jersey Gov. Chris Christie, or Texas Gov. Rick Perry. But here's my question: When has this ever happened?

By "this," I mean the white knight candidate riding in after the race has started to save his party from a bunch of unpalatable choices. Whenever there isn't an early front-runner or an obvious choice (like a sitting or former vice president), the field tends to be mocked as weak (you may remember the Democrats' "seven dwarves" from 1988). When that happens, there is always someone people are trying to pull into the race; notable previous examples include Mario Cuomo and Colin Powell. But is there a single case from the modern era of primary campaigns (which began in 1972; I'll spare you the lecture on the McGovern-Fraser Commission reforms) in which someone entered the race relatively late after not being sure they wanted to run, then won the nomination and the presidency?

The answer is no. In every single election, the nominees are people who knew they were running and began preparing long before the race began. Every once in a while you get a late entry like Fred Thompson in 2008, but they always fail. Republicans need to get used to the idea that the white knight is not coming.