Obama's economic message is clearly aimed at middle-class families that have seen prices rise and incomes stagnate. This is his clearest advantage. And he pressed it in his speech tonight here:

Now, I don't believe that Senator McCain doesn't care what's going on in the lives of Americans; I just think he doesn't know. Why else would he define middle-class as someone making under $5 million a year? How else could he propose hundreds of billions in tax breaks for big corporations and oil companies, but not one penny of tax relief to more than 100 million Americans?

And here: "I will cut taxes - cut taxes - for 95 percent of all working families." And here: "If you have health care, my plan will lower your premiums." And here: "But I will also go through the federal budget, line by line, eliminating programs that no longer work and making the ones we do need work better and cost less - because we cannot meet twenty-first century challenges with a twentieth-century bureaucracy." McCain can respond to these assertions by pointing out that Obama would raise the overall tax burden, support a renewal of the ban on offshore drilling, and has no record of spending cuts. That may not be enough, however. Because McCain's lack of a middle-class tax cut remains his key domestic policy liability.