Theodore H. White wrote that you should think of voters as a series of boxes; white, black, union, office worker, stay at home mom, student, corporate president, business owner, etc. and that the candidate who could tie up enough of those boxes and deliver them to the voting booth would end up the winner.

Barack Obama isn't tying up the box marked "white" and his current level of support suggests that he will lose the election.

RealClearPolitics:

What if Obama doesn't even match Dukakis with whites? That's the dynamic of 2012. This electorate has a white floor. And it has broken for this president. Democrats cannot depend on demographics to save them.

Should Romney win the whites Obama lost, Romney will only need to perform as well as John McCain with minorities to win. This is true even under Democrats' most optimistic, and unlikely, demographic scenario: that the white share of the electorate decreases another two percentage points from 2008, blacks turn out at the same historic levels they did then, and the Hispanic share of the vote rises from 9 to 11 percent of the electorate while Obama retains the same level of support from other minority groups.

The white margin to watch: 61-39. That's the rough break-even point. Obama likely needs more than 39 percent of whites to assure re-election. Romney likely needs at least 61 percent of whites to assure Obama's defeat (or 60.5 in some scenerios). These are estimates based on an electorate that matches the diversity of 2008 or is slightly less white. It presumes the Electoral College outcome does not diverge from the winner of the popular vote (loose talk aside, it's only happened four times in U.S. history).

Thus, Obama can do a little worse than Dukakis, and Romney must perform a little better than Bush circa 1988. Whites favored Reagan in 1984 by a 64-35 margin. They favored Bush in 1988 by a 59-40 margin. Four years ago, whites favored McCain by a 55-43 margin.

Only 37 or 38 percent of whites back Obama today, according to the Gallup Poll's authoritative weekly averages since early April (which have a larger sample size than most polls combined). The rub for Romney? In those same matchups, Romney only wins 54 percent of whites. Other surveys show the same. CNN's latest pegged the white margin at 53-39. FOX News' latest, 51-35. Ipsos-Reuters, 53-38. The Pew Research Center's polls have, however, shown Obama stronger this year. Its recent survey placed the margin at 54-41.

It's a tall order for Obama to match the turnout among minorities he got in 2008. The magic is gone -- even with his black base. Hispanics are happy about his DREAM act power grab but will they turn out this time? The young appear dispirited by Obama's trail of broken promises. And the Jewish vote may surprise us as the president appears to have lost significant support there.

Romney doesn't have to work for the white vote. But he has to advance an agenda that appeals across a broad spectrum of Americans. Only then will the swing voters fall his way and give him the election.