John McCain's choice of Sarah Palin was the most inspired decision of his long race for the White House. The ads lampooning Barack Obama's messianic pretensions were skillful as well. But the Palin pick accomplished several goals at once. It is, it must be acknowledged, a terrible year to be a Republican. A decidedly unpopular Republican president is finishing his second term. Republican party identification is at its lowest point in 16 years (27 percent, according to the Pew Research Center). All indicia of excitement — money raising, turnout at political events, buzz — strongly favor the Democrats. Further, the...