Class is always an ironic issue in American politics, and the irony this time is particularly poignant. We are in the midst of a great national debate about how to make health care affordable; almost nothing is more important to working-class Americans. “For the health of the nation, both physically and economically, we need a system with a public option,” Leo Gerard, president of the United Steelworkers, wrote recently in the Huffington Post. “And we need it now.”

But whether working families get it now depends to a large degree on Mr. Obama’s personal popularity. And now comes Gates-gate, this latest burst of fake populism from the right. Waving the banner of the long-suffering working class, the tax-cutting friends of the top 2% have managed to dent the president’s credibility, to momentarily halt his forward movement on the health-care issue.

Umbrage at a Harvard professor’s class snobbery, in other words, might derail this generation’s greatest hope for actually mitigating the class divide.