Obama: “My Grandmother’s the Last One Left”

The Senator tells CBS' "Early Show" about the urgency he feels to visit his ailing grandmother, with less than two weeks before Election Day.

Says he arrived too late at his mother's bedside before she died, and "I want to make sure that I don't make the same mistake twice."

Plus: Acknowledges "politics is tough," but says McCain's campaign is saying "the kind of stuff that I can't imagine saying about an opponent of mine."

Watch video above. Read transcript here.