Last week, a few dozen hedge fund and investment executives arrived at the Park Avenue home of Hamilton E. James, president of the private equity firm Blackstone. Each had paid $35,800 to spend two hours at a fund-raiser with President Obama, but the timing proved awkward: A few hours earlier, Mr. Obama’s campaign had begun a blistering attack on Mitt Romney’s career in private equity, the same business in which Mr. James has earned his many millions.

“Campaigns do what campaigns have to do,” Mr. James later told friends. But not everyone was as forgiving. “People were incredulous,” said one person who attended the dinner. “They could have waited a week.”

Debates over how much to blame — and regulate — Wall Street have stoked tensions between Democrats and the financial industry ever since Mr. Obama took office amid a financial crisis. But now Mr. Obama is leveraging his bully pulpit and advertising dollars to argue that Mr. Romney’s career as a successful financial executive exhibited values that are not those of a good president.

In doing so, he has not only drawn criticism from allies like Steven L. Rattner, the investor and former adviser on the auto industry, and Cory A. Booker, the mayor of Newark and a favorite of New York’s hedge fund world. Mr. Obama may also be testing a bond first formed by Bill Clinton, who persuaded much of his party’s elite that Democrats could be both populist and friendly to Wall Street.