For all of the numbers swirling around the presidential campaign as the nominating conventions approach, each side's equation for success can be succinctly expressed.
For President Obama, the winning formula can be reduced to 80/40. In 2008, Obama won a combined 80 percent of the votes of all minority voters, including not only African-Americans but also Hispanics, Asians, and others. If Obama matches that performance this year, he can squeak out a national majority with support from about 40 percent of whites — so long as minorities at least match the 26 percent of the vote they cast last time.
Obama's strategic equation defines Mitt Romney's formula: 61/74. Romney's camp is focused intently on capturing at least 61 percent of white voters. That would provide him a slim national majority — so long as whites constitute at least 74 percent of the vote, as they did last time, and Obama doesn't improve on his 80 percent showing with minorities.
These calculations underscore the depth of racial polarization shadowing this election and the achingly slim margin of error facing each candidate. If Obama nudges past 80 percent among minorities (which seems very possible) or the minority vote share rises (also possible, though less probable), the president could gain reelection while winning only about 38 percent of white votes. Conversely, if the white proportion of the vote increases just a single percentage point (to 75 percent), and Romney records any gains among minorities, he could shave his winning number to a more manageable 59 percent of whites.
On its face, the math is tougher for Romney. If he reaches 61 percent among whites, he would equal the best performance ever for a Republican presidential challenger with that group of voters: Dwight Eisenhower in 1952, Ronald Reagan in 1980, and George H.W. Bush in 1988 each won between 56 percent and 61 percent of white voters, according to polls at the time.
If white voters maintain their 2008 share of the vote, that in itself would represent a significant shift. Whites have declined as a portion of the electorate in every presidential election since 1992, according to exit polls.
That streak might end in November. Obama could face both a numerator and a denominator problem in the electorate's racial composition. The denominator problem is that turnout among conservative white voters could be much higher than in 2008. The numerator challenge is that economic dislocation, disappointment in Obama, and voter-identification laws passed in Republican-controlled states could depress minority turnout.
And yet it would be dangerous for Republicans to bank on a declining minority presence. Census figures show that the minority share of eligible voters has increased to nearly 29 percent; smaller turnout from that larger pool still could produce a minority vote share equal to, or greater than, that of 2008. Republicans could blunt the impact of minorities by winning more of them, but Romney's campaign seems to have no concrete plan for how to do that after a primary season when he veered so far to the right on immigration.
Obama's situation is hardly secure either. He might need only about 40 percent of whites to win (compared with his 43 percent in 2008), but his approval rating among those voters has often fallen short of that, and Democrats couldn't reach that level in the 2010 House races.
The easiest way to view whites' voting tendencies is through the prism of education and gender. In 2008, Obama won a 52 percent majority of white women with at least a four-year college degree; these voters tend to be socially liberal and open to activist government. But he captured just 43 percent or less among the other three quadrants of whites: men with college degrees, and white men and women without them.
Romney's team hopes to increase his vote share to three-fifths among college-educated white men and two-thirds among blue-collar white men. But his advisers believe the election will be decided mostly by whether Romney can make smaller gains among white women. Most polls show Obama maintaining or exceeding his strong 2008 showing with college-plus white women (he's polling above 60 percent with them in some key states); Romney's campaign hopes to recapture some of these voters by stressing the increased federal debt their children will inherit after Obama's term. Romney's team considers it even more imperative to reverse the recent gains that Obama has recorded among blue-collar white women by his effective portrayal of the GOP nominee as an out-of-touch plutocrat. Attacks against Obama's record on spending and welfare will be Romney's key strategy there.
Republican strategists clearly feel the weight of trying to assemble a national majority with so little support among minorities that they must win three in five whites. "This is the last time anyone will try to do this," one said. A GOP coalition that relies almost entirely on whites could squeeze out one more narrow victory in November. But if Republicans can't find more effective ways to bridge the priorities of their conservative core and the diversifying Next America, that weight will grow more daunting every year.