In 2008’s election, many Republicans and independents voted for Mr. Obama to put a final nail in the coffin of Justice O’Connor’s racial anxieties. The millions of them who then cast votes against Mr. Obama in 2012 did so almost wholly because of the status of the economy after four years of his presidency. No matter. They lost in 2012 because they’re “too white.”

This country’s historic antidote to racial and ethnic obsessing is assimilation into the middle class, no matter what foreign country or continent sits in front of your hyphen. To this end the Republican candidate offered a solution led by private enterprise, and the Democrat said government should create the path forward. Mr. Obama won and has the four years he asked for to finally make good on his economics. But even this common goal degrades into a cudgel in the president’s politics by category: tax cuts for the middle class but not for “the well-off.”

The Democrats’ insistence on pandering to political categories is a dead end for the country. Rather than spinning their own Rubik’s Cube of race, gender and ethnicity, Republicans should start growing their share of the electorate by doing a better job of telling people how to succeed in the American melting pot, a wonderful organizing idea now mocked as a “myth” by progressive Democrats.