PRESIDENT OBAMA isn’t backing down from his campaign ad attacking Mitt Romney’s private equity firm, Bain Capital. Actually, “attack” may be too weak a description for a video that likens Bain to “a vampire” and depicts Mr. Romney as a plutocrat who callously destroyed hundreds of steel jobs for his own enrichment. Several prominent members of Mr. Obama’s own party thought the commercial was a bit over the top. (Not to mention highly derivative of previous ones financed by backers of Mr. Romney’s Republican primary rivals.)

Still, politics ain’t beanbag, and, if he’s going to tout it as a qualification for the White House, Mr. Romney’s business record is indeed fair game. The more pertinent question is what to make of Mr. Obama’s defense of the ad, which he offered at a news conference Monday.

Mr. Obama suggested that he never meant to condemn the private equity business as a whole. “I think there are folks who do good work in that area and there are times where they identify the capacity for the economy to create new jobs or new industries,” he noted. Instead, he added, he meant simply to point out that a career in private equity is not appropriate preparation for the White House. There’s a big difference between what it takes to “maximize profits,” a perfectly legitimate goal in the business world, and what it takes to “figure out how everybody in the country has a fair shot,” which is the job of a president, he said.

On one level, it’s reassuring to learn that the president has a nuanced view of private equity, a business that has been rightly praised for revitalizing many a struggling enterprise — and rightly criticized for loading up many rescued firms with debt to pay off investors. Of course, those investors include public employee unions’ pension funds, which had entrusted $220 billion to private equity as of fall 2011, according to Wilshire Trust Universe Comparison Service.

The president accepted $3.5 million in campaign donations from private equity executives in 2008, and additional dollars this time around, so it would have been awkward for him not to concede that private equity does “good work.” As for the ad’s depiction of job destruction, economists at the National Bureau of Economic Research found that firms restructured by private equity suffered net job losses over five years only 1 percent greater than other comparable companies.

Yet the minute Mr. Obama conceded those complications — admitted, in effect, that the private equity business, like most endeavors, involves tradeoffs, and that its benefits might be shared among more than a handful of fat cats — he undercut his distinction between “maximizing profit” and the common good. He also undercut his case against Mr. Romney, since Bain had its share of success stories on the former Massachusetts governor’s watch.

What we’re left with is a president who seems content to present an even-handed view of private equity at his news conferences while propounding a much more tendentious one in his campaign advertising. Pointing out that a business career hasn’t fully prepared Mr. Romney to be president, in other words, is a long way from suggesting that he’s a vampire.