After Booker Criticisms, a Struggle to Define What's Fair Game Mr. Obama's advisers insist that their full-throated assault on Bain Capital, now in its second full week, is intended as a critique of Mr. Romney's claims to be a jobs creator. But much of the commentary on Mr. Obama's behalf describes Mr. Romney in highly personal and unflattering ways. That approach has begun to have consequences. On Sunday, Cory A. Booker, the mayor of Newark and a top supporter of Mr. Obama's, called the descent into personal attacks "nauseating" and said both campaigns should stop the "crap" they have been offering the public. "This, to me, I'm very uncomfortable with," Mr. Booker said on NBC's "Meet the Press" program. A few hours later, Mr. Booker released a three-minute video backing off his criticism of the president and trying to draw a distinction between personal attacks and legitimate criticisms of Mr. Romney's time at Bain. In the video, he said it is "reasonable" for Mr. Obama's campaign to examine his rival's business record. Mr. Booker's first instinct may have been influenced by his ties with Wall Street executives, many of whom are his supporters. Other Democrats who have criticized the Bain attacks - like Stephen Rattner, Mr. Obama's former auto czar - are also close to the private equity world. But the episode involving Mr. Booker suggests that Mr. Obama is walking a fine line as he tries to make Bain Capital a central issue in the presidential campaign. Both candidates are eager to attract independent voters who may be turned off by attacks they think cross a line of decency. And Mr. Romney has jumped at the chance to argue that the president has done just that. Last week, Mr. Romney said the Bain attacks from Mr. Obama were intended to suggest that "I'm not a good person, or a good guy." The Republican party sought to stoke the issue further on Monday, using video of Mr. Booker's "Meet the Press" comments to raise money with an e-mail that says, "I Stand With Cory." The Republican National Committee also launched an "I Stand With Cory" petition drive and began using the #StandWithCory hashtag on Twitter. And Mr. Romney's campaign produced a video alleging that Mr. Obama's supporters have "had enough of President Obama's attacks on free enterprise." Mr. Obama's campaign has dismissed that criticism, saying its Web site - romneyeconomics.com - is an effort to describe how the values Mr. Romney's pursued at Bain would color his actions as president. "This is not about private equity or how Romney ran his company," Stephanie Cutter, a deputy campaign manager for Mr. Obama, told reporters recently. It's about whether his business experience there qualifies him to be president. But the campaign ads and conference calls are frequently platforms to question Mr. Romney's personal qualities. A video released Monday by Mr. Obama's campaign highlights an office supply company whose workers were fired when it was bought by a Bain company. In the ad, the workers deride Mr. Romney's personal ethics. One says that Mr. Romney "did not care about us as workers." Another says that Mr. Romney "takes from the poor and the middle class and gives to the rich. He's just the opposite of Robin Hood. A third says flatly: "You can tell by the way he acts, the way he talks. He doesn't care anything about the middle-class or the lower-class people. In another ad, set at a Kansas City, Mo., steel plant, Joe Soptic, a former worker there, says as president, Mr. Romney "would be so out of touch with the average person in this country. How could you care? How could you care for the average, working person if you feel that way? Mr. Soptic went even further in a conference call with reporters, saying that Mr. Romney "is only worried about one group of people, and that's people like him, people at the top." The personal criticisms of Mr. Romney also come directly from Mr. Obama's campaign officials. In the conference call with Mr. Soptic, Ms. Cutter said the issue was Mr. Romney's personal values. "Romney didn't care about rewarding hard work or responsibilities," she said. It's absolutely on the table as an indication of Romney's values. That message is being echoed in "super PAC" ads on the campaign's behalf. An ad by Priorities USA Action concludes with a worker saying that Mr. Romney "promised us the same things he's promising the United States. He'll give you the same thing he gave us. He'll take it all. To be sure, Mr. Romney's campaign has been aggressive in describing Mr. Obama in personal ways. Mr. Romney repeatedly says that the president "doesn't get it," painting Mr. Obama as a kind of slow-learning neophyte in the Oval Office. His campaign often describes the president as a liar, saying he personally broke promises he made to the American people. And the Republican super PACs have targeted Mr. Obama personally. The Times reported last week on a plan by one of them to link Mr. Obama to his former pastor, the Rev. Jeremiah Wright. The question may be whether either campaign is making progress with voters by making the issues more about the candidates and less about the policies they pursue. Mr. Booker, the mayor of New Jersey's largest city, said on "Meet the Press" that the trash talk was crowding out more serious conversations about the economy and other issues. And in his video clarification, he continued to urge the candidates to stay away from the personal attacks. "My concern is we are about to go into a significant political campaign that will affect the destiny of our nation," he said. I am, indeed, upset. I am, indeed, frustrated. But I believe the American public, working together, we can begin to more and more denounce this type of campaigning. "Ultimately," he added, "my hope is that this election will not therefore be about the small things, will not be about divisiveness, will not be about denigrating, will not be about painting with a broad brush."