Romney’s key weakness — the place where he most needs to improve his performance — is that he isn’t seen as a champion of middle-class interests. In this week’s NBC/Wall Street Journal poll, Obama is leading him by 19 points on the question of who would be the best at looking out for the middle class. This weakness is what underlies every other one Romney has, from his low favorability ratings to Obama’s advantage in the head-to-head numbers. Romney doesn’t need to make the case that he would help the middle class at the expense of the rich; that’s Obama’s play. But he does need to emphasize, again and again, how his agenda would help the vast majority of Americans.

It would be easier to make that case if Romney had advanced a plan to replace Obamacare that would tear down the barriers that keep millions of people from being able to buy health insurance, or if he had embraced a middle-class-friendly tax reform such as an expansion of the child tax credit. But it’s too late in this campaign to expect much in the way of new policy initiatives. Romney will have to make use of what he’s got — and that’s actually quite a bit.

So: Run ads pointing out that his energy policies will create jobs and lower prices, that he will block Obamacare’s middle-class tax increases and will replace them with policies that allow people to keep and buy their own insurance, that his tax reform will lead to higher growth and therefore higher wages.