How else to explain what he's doing in Iowa? McCain got a late start there and the state seems to be somebody else's to lose -- just like Huckabee in the primaries. Now, he's outspending Obama on media there, holding rallies, and dumping money into aggressive robocalls targeted at flood victims, even though Obama consistently polls ahead by more than ten points.
He must believe his choice of Sarah Palin will awaken the Huckabee brigades, who made up for their candidate's ground-game deficit by organically organizing in their churches and home-school groups and swamping the polls. Huck's win seemed like a miracle at the time, and when people need some supernatural rescue of their own, they like to visit the sites where miracles were worked in the past.
But there are, to put it mildly, great differences between Huck's situation in the primaries and McCain's now. Huck was simply unknown in Iowa, whereas McCain is known and disdained. (Insulting ethanol will do that to you.) And Huck was up against a default choice -- Mitt Romney -- whereas McCain is up against a near native son, the man Iowans proudly take credit for launching. Even though the Huckabee brigades, who probably would respond well to Palin, surged, Obama got more than twice as many votes in the Iowa Democratic primary as Huckabee did in his.