Mr. Obama will stay on message in Denver, redirecting his opponent and interrogator to the economy before he was president (or even in politics)—”challenges that have built up over decades”—and about the wind-driven economy that will exist after he’s re-elected. But not about the economy in between. If this were an episode of “Homeland,” Mitt Romney’s first question to his evasive competitor would be: “Mr. President, what are you hiding?”

It’s true, as Mr. Obama argues, that the numbers of unemployed Americans began to rise abruptly after September 2008 when the financial crisis erupted, and that the president’s name then was George W. Bush. What Mr. Obama won’t say is that the financial crisis resulted from the implosion of a housing market transformed into a toxic landfill by Congress, regulators, Fannie, Freddie and mortgage packagers. The Bush presidency was a bystander. …

Also left unsaid by Mr. Obama but free for the telling by Mr. Romney is that as the U.S. unemployment rate hit 9.5% in June 2009 and a shocked public was looking for a response, the new president introduced the Affordable Care Act. Whatever else one may say about ObamaCare, it has nothing directly to do with U.S. employment. For the next nine months, as unemployment ran between 9.5% and 10%, Congress at Mr. Obama’s insistence worked on his health-care legislation. When Mr. Obama signed the bill into law in March 2010, the unemployment rate was 9.8%. If an opponent wanted to describe this in partisan terms, he might say that the president legislated an entitlement dream while the economy burned.