Marc talks to his sources:

McCain advisers say they're saving their best material for the last ten days of  the race, when, the campaign hopes, three quarters of the remaining undecided voters will make up their minds, and their minds will be concentrating on Barack Obama. When the urgency of the presidential election impresses itself, the hope is that these voters will swing back to the familiar, rather than the unknown.  The last ten days, according to a McCain aide, are when the "imponderables" come into play.

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