Manish Vora, research director at Monnes, Crespi, Hardt and Co., a New York equity research firm, attended an Obama event in the Big Apple in March. The 27-year-old undecided voter said he was blown away at how many young professionals showed up; he knew 30 people there.

"You looked around the room and everyone essentially was under the age of 30. It was sort of like waiting for a concert, it was definitely a different feeling," he said.

Change is a common thread for many Obama backers. Frank Sanchez, C.E.O. of Renaissance Steel in Tampa, Florida, says backing Obama over Hillary Clinton was not "a light decision"—not least because Sanchez was an assistant secretary of transportation in Bill Clinton's administration.

For him, the decision to support Obama over Hillary was about sending a message that the U.S. would change. "I feel in this situation, we have a unique opportunity to bridge gaps in our own country and throughout the world," he says.

Financially, the Obama and Clinton camps are the two powerhouses in the eight-person Democratic primary race. Although Clinton raised more than Obama this summer—$22 million for her versus $19 million for him—the two are virtually tied in cash on hand to use for the primary elections, according to the Center for Responsive Politics.  

As of September 30, Obama, who has eschewed money from registered lobbyists and  political action committees, has raised a total of $80.3 million, while Clinton has raised $90.9 million.

According to the Campaign Finance Institute, Obama's small donors account for 28 percent of his total primary money raised from individuals; Clinton's account for 13 percent.

Supporters say these smaller contributors—many of them new to politics and the Democratic Party—responded to Obama's optimism.

"For the first time in maybe a generation, here's somebody who says, 'Government can be a good thing if we can just get our politics right. If we stop being so partisan, if we get special interests out, if we stop the gridlock in Washington, government can actually solve some of our problems,'" Solomont says.

"And that," he adds, "is what's attracting people who [Al] Gore and [John] Kerry and even [Bill] Clinton didn't necessarily attract."

Aaron Nurick, professor of management and psychology at Bentley College in Massachusetts, says Obama is seen as someone with new ideas. "Business executives are very taken with somebody who is very articulate for their vision and sort of does lay out their plan for change," he says.

Executives "enjoy hearing a message of someone they think can be a real change agent even if that person doesn't come with a real deep portfolio of experience," Nurick says. "I think they're really tired of the way things are happening in Washington. That's true for a lot of people but I think business executives are on the vanguard on that.

While courting business executives, Obama has also taken some positions that could put business support at risk. He has proposed increasing the tax burden on companies and investors to let him cut taxes on the middle class by more than $80 billion annually.

Obama was among the Democrats who have pushed to more than double the tax rate on the huge earnings of private-equity managers. When that proposal was bottled up in Congress, his reaction was swift and pointed:

 "If there was ever a doubt that Washington lobbyists don't actually represent real Americans, it's the fact that they stopped leaders of both parties from requiring elite investment firms to pay their fair share of taxes, even as middle-class families struggle to pay theirs," he said in a statement.

"When I'm president," he added, "I will close tax loopholes for big corporations, provide 90 percent of working Americans with a tax cut, and pass the strongest lobbying reform in history."

Dornbush said Obama's thoughtfulness is what drew him to the candidate. When he sat down with Obama in January and talked about his biotechnology business, which is pursuing the therapeutic use of a protein to battle macular degeneration and cancer, Dornbush said he was impressed.

"You could really just sort of see him taking this information in and processing it and really just hearing how challenging it is, drug discovery," he said. "You could see the brain sort of turning."