Despite a growing backlash from his fellow Democrats, President Obama has doubled down on his attacks on Mitt Romney's tenure at Bain Capital. But the strategy could backfire in ways Obama has not anticipated. After all, if Romney's record in private equity is fair game, then so is Obama's record in public equity — and that record is not pretty. Since taking office, Obama has invested billions of taxpayer dollars in private businesses, including as part of his stimulus spending bill. Many of those investments have turned out to be unmitigated disasters — leaving in their wake bankruptcies, layoffs, criminal...