Obama led with the best sales pitch he has to offer: that he is not George Bush. But of course, Obama is running against John McCain, not Bush. So he attempted to justify the substitution by claiming that "John McCain has voted with George Bush ninety percent of the time." This statistic has been used throughout the Democratic convention, but it makes no sense. Bush is not a member of Congress and casts no votes there--so how can you compare his voting record to that of McCain?
When it came to making the positive case for himself, Obama's first goal was to address the public's concerns about his background, particularly his patriotism and how much he identifies with American values. So he drew, not from his own biography, but from that of his family.
In addition to identifying himself with the lower-income, blue-collar types who have so far refused to vote for him, Obama is also painting himself as someone with uncontroversial, traditional American values, someone who believes in fighting for your country and improving your life through hard work and perseverance.
This is supposed to make us forget that Barack Obama launched his political career under the spiritual guidance of a pastor who delivered far-left tirades calling on God to damn America--and he launched his first campaign under the patronage of a former domestic terrorist. Theirs are the stories that also shaped Barack Obama--but he wants to write Jeremiah Wright and William Ayers out of his biography.