Because Romney's earnings come from funds run by Bain and other investment vehicles, his tax rate in 2010 was 13.9 percent, according to documents his campaign released earlier this year.

Carried Interest

Both candidates have pledged to pursue broad reform of the U.S. tax code, which is likely to include a reconsideration of carried interest and capital gains, Purple Strategies LLC's Richard Keil said.

"Regardless of who wins, if there's any attempt at comprehensive tax reform, it's impossible to imagine that changes to carried interest aren't part of the original draft or an amendment," said Keil, whose Washington-area firm was founded by a group of Republican and Democratic strategists.

Another promise Romney may not be able to keep is the repeal of the 2,300-page Dodd-Frank law that Obama signed two years ago. Since then, bankers have been fighting the regulation's provisions, which include stricter capital requirements and the so-called Volcker Rule that bars deposit- taking banks from making wagers with their own money.

Obama's Backers

The lobbying effort was gaining traction until May, when JPMorgan Chase & Co. reported a $2 billion-plus trading loss from a portfolio of credit derivatives. Jamie Dimon, the bank's CEO, was called to Washington twice to testify before Congress and the losses have prompted talk among lawmakers about capping the size of Wall Street firms.

Obama still has a few hedge-fund and private-equity managers who have come out to support him.

Tony James, president of private-equity and real estate giant Blackstone Group LP, hosted Obama in May at his apartment on New York's Fifth Avenue. Blackstone executives including Jonathan Gray, real estate chief, and Joan Solotar, the head of external affairs, were on hand, according to people familiar with the event.

Marc Lasry, founder of Avenue Capital Group LLC, held a well-publicized party for Obama in early June. About 50 people came to his apartment, paying $40,000 for a 90-minute question- and-answer session with Obama and former President Bill Clinton. "It's not every day you get to be in a room with two presidents," the e-mail invitation said.

If Obama ends up winning in November, Wall Street can take comfort that there will be few surprises from the president in his second term.