This Convention Is About A Number

Depending on the measure, Obama receives the support of about 80% of people who describe themselves as Democrats. John McCain receives the support of at least 85% of those who describe themselves as Republicans.

Now -- in this cycle, many more Americans describe themselves as Democrats than Republicans. The two split independents, but the party ID gap explains why Obama is still slightly ahead of McCain nationally. He has better standing among virtually every demographic group now than John Kerry did at the time of his election. Among all groups...but people who call themselves Democrats. (Kerry won Democrats 89-11.)

Obama will try to use this convention to increase his standing among Democrats. This convention is NOT aimed at persuading people who call themselves independents and moderates. It's about persuading people who lean left and call themselves Democrats but who, for many reasons, aren't sure about Obama.

They are, yes, Hillary supporters, but a certain type of Hillary supporters: mainly white voters without college degrees. Ron Brownstein has noted that in four polls taken before the convention, Obama sits at 38% with this group.  These voters, as pollster Stan Greenberg's new data shows, have a panoply of concerns. Unquestionably, some are racist. But a majority of them worry about Obama's credentials, his liberal positions on national security issues, and whether he truly understands their economic insecurities.

It is much easier to convince these voters to vote for Obama when they see Obama as the antidote to the Bush presidency, and when they see McCain as a Bush Republican. SO -- you will hear and see speaker after speaker portray McCain as a Bush Republican.  Polling shows that even when recalcitrant Democrats learn about Obama's middle class roots, they're still skeptical. It is MUCH harder to convince them to vote for Obama because they LIKE him. It is much easier to convince them to vote for Obama because they think McCain represents a continuation of President Bush's policies. (Obama's campaign has polling data suggesting that an unusually large number of pro-choice Democrats don't know that McCain is pro-life.)