The recent direction of Mitt Romney's campaign may seem perplexing —  the candidate's birther joke, those ads accusing Obama of gutting welfare reform, John Sununu's jab that Obama needs to learn how to be American, and veep pick Paul Ryan's pride at bitterly clinging to guns and God — but it can all be explained with just one number: 61 percent, which is the share of the white vote Romney needs to win.

In June RealClearPolitics' David Paul Kuhn looked at the demographic break down in vote projections and concluded, "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." To put that into context, Kuhn notes, "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." When Kuhn was writing in late June, he noted in an average of four polls, Obama was a couple points below the 39 percent mark -- and Romney was far from his 61 percent target. The New Republic's Nate Cohn pointed out that averaging more polls, whites were splitting for Romney by 52 percent to 39 percent. With Romney making little headway with black or Hispanic voters — polls typically put his support among non-white voters in the high teens to low 20s — the best remaining option is to get to that 61 percent threshold with whites. And if the Republican primary taught us anything — think back to Donald Trump's birther bubble and Newt Gingrich's South Carolina victory after doubling down on his charge that Obama is the "food stamp president" — these racially tinged campaign barbs are sure crowd pleasers among white Republicans. 

Of course, as Jonathan Chait explained in New York back in February, the G.O.P.'s demographic reliance on white voters is a strategy with an impending expiration date. Whites have been a shrinking portion of the electorate election after election, so even though George H. W. Bush crushed Michael Dukakis in 1988, because of the demographic changes in the American population if Obama got Dukakis's share of whites in 2008 -- and everyone else voted the same way they did four years ago -- Obama would still have won. But that's long-term thinking. Romney only has 73 days left to win this election and the best bet he has left is to boost his margin among white voters and hope the non-white turnout is a lot lower for Obama.

However, since clinching the Republican nomination — largely by staying out of the day-to-day cable controversies of the primary and letting his opponents self-destruct — Romney hasn't made much progress among white folks. A poll released Friday by CNN/ ORC International shows a close race — Obama winning 49 percent of likely voters, and Romney winning 47 percent. That should be great news for Romney. But if you look more closely, he's still got to get white people to love him. The CNN poll shows Obama getting 40 percent of the white vote, 1 point better than he needs, and Romney getting 56 percent, 5 points less than he needs. 

A recent Fox News poll (conducted from August 19 to August 21) showed a poorer standing for Obama among whites, with just 36 percent voting for him. But even there, Romney was only winning 53 percent of white votes. Overall, the poll showed Romney ahead 45 percent to Obama's 44 percent. A Monmouth University poll conducted from August 15 to August 19 showed Obama with 39 percent of whites and Romney with 49 percent of whites. Polls in swing states like Ohio and Wisconsin show Romney still has a ways to go.

In other words, Romney needs to be more loved by white people and Obama needs to be more disliked by them for Romney to win. Romney made a step toward that goal Friday with his birther joke, "No one’s ever asked to see my birth certificate. They know that this is the place that we were born and raised." Romney defended his comments, saying of his mostly-white audience, "the crowd loved it and got a good laugh."