AT WHICH POINT HE NEEDS ONE HECK OF A LOT OF DEMOCRATS TO TURN OUT:

In the last three releases of the tracking poll conducted by The Washington Post and ABC News, Obama has trailed former Massachusetts governor Mitt Romney among independent voters by between 16 and 20 percentage points.

That's a striking reversal from 2008, when Obama won independent voters, who made up 29 percent of the electorate, by eight points over Sen. John McCain of Arizona.

And if Romney's large margin among independents holds, it will be a break not just from 2008 but also from 2000 and 2004. In 2000, Texas Gov. George W. Bush won independents by 47 percent to 45 percent over Vice President Al Gore. Four years later, Bush and Sen. John F. Kerry of Massachusetts essentially split unaffiliated voters, according to exit polls -- 48 percent for Bush to 49 percent for Kerry. 

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