Sarah Palin can’t be underestimated; she could still grab the nomination since no one else has taken off. A lot would depend on whether, a year from now, Republicans see President Obama as ripe for the picking. If Obama can be beaten, then the G.O.P. may turn a bit cautious and try to choose someone who can capture swing voters. That isn’t Ms. Palin’s profile. In trial heats she fairly consistently loses to President Obama by the widest margin of all the better known G.O.P. candidates.

Yet if the economy is much better and the president looks to be romping to a second term, Republicans may just go with their hearts and not their heads. They’ve done it before, with Barry Goldwater in 1964. The G.O.P. was wild about Goldwater, who garnered 38 percent and lost to President Lyndon Johnson in one of the biggest landslides in history.