Campaigning for public office on a platform that demonizes the wealthy is not a new idea. In a speech to the 1936 Democratic National Convention in Philadelphia, for instance, Franklin D. Roosevelt accused "economic royalists" of standing in the way of income equality.

The theme emerges periodically in political campaigns, usually as part of a larger, more issue-oriented strategy. President Obama, though, has made it the centerpiece of his reelection bid. He has attacked presumptive Republican nominee Mitt Romney's record as an executive of Bain Capital, the private-equity firm that reaped enormous financial benefits from investments in distressed companies, making Romney a multimillionaire.

Not all of Bain's ventures turned out well — that's why they're called "ventures" — so bankruptcies, factory closings, and unemployment dot its record. Obama's campaign has seized on those failures, accusing Bain and Romney of enriching themselves at the expense of American workers. Romney has responded by pointing out that failures are part of the business, and that Bain's success in retaining and creating thousands of jobs far outpaces the failures.

Presumably, the Obama campaign settled on its line of attack after testing it with focus groups and polls. It has hammered away at Romney and Bain to the exclusion of other issues. In doing so, however, Obama risks appearing to have so little confidence in his record that he has decided to distract voters with a relentless assault on Romney's past business dealings.

The strategy supposes that Americans resent the wealthy and will take their anger out on the Republican in November. But it is not at all clear that the resentment embodied by the Occupy Wall Street movement is either widespread or very deep.

In fact, polls reveal that Romney's ability to address the nation's economic problems is generally regarded as equal to or slightly better than Obama's. In fact, Romney's private-sector successes may be seen as making him more qualified to deal with economic and employment issues.

The president insists that he is not attacking the private-equity industry, only Romney's record as a leader in it. This suggests a level of subtlety and nuance that rarely comes across in political campaigns. A campaign theme whose success depends on voters' ability and willingness to parse it is problematic.

A number of prominent Democrats, including Newark Mayor Cory Booker, have gone public with concerns about the direction of the Obama campaign, warning that it could be interpreted as attacking capitalism itself. Obama also risks appearing small-minded and mean-spirited in emphasizing negativity over his own vision and purpose. It's likely these concerns have also been expressed privately in more colorful terms, though to no apparent avail.

Romney's record at Bain certainly should not be immune from campaign scrutiny. He has, after all, touted his success there as a principal qualification.

But by focusing on instances in which Bain's investments came up short, the Obama campaign has exposed itself to attacks on the president's record of high unemployment, low consumer confidence, and unprecedented debt and deficits. It also gives Romney an opening to recount Bain's successes and deliver a message that contrasts sharply with the president's.

Midcourse campaign corrections are difficult to manage without appearing desperate. Should internal pressures continue to build, though, and if polling reveals minimal damage to Romney, the president may have little choice but to attempt one.