Obama’s best bet is probably to hit Romney again and again over his plans for Social Security and Medicare. That’s a big issue: Nothing Romney is proposing would be more consequential. And it’s an issue where Obama can draw on strong public sentiments. Most people believe the programs need reform. But in a Pew poll in 2011, Americans favored preserving benefits to reducing deficits by almost 2-to-1. By 56 percent to 33 percent, they worried more about Social Security benefit cuts than about tax increases. In a March 2012 poll, just 26 percent of the public favored the Republican idea of changing Medicare so that beneficiaries pick a health plan and get a “fixed sum of money” to meet the costs.

A defense of the two entitlement programs as now structured would not be the most edifying of spectacles. It would require Obama to foster the false impression that the approaching insolvency of our welfare state has painless solutions. But it would force Romney to confront the issue head-on, and the country would get the important debate it deserves rather than months of sniping about trivial side- issues and non-issues.

It seems more likely than any of Obama’s other options to win him a second term.