"Before the Internet, unless you had a really good direct mail database, it didn't make sense to focus on small donor fundraising because it cost about almost as much as it brought in," said Carol Darr, director of the Institute for Politics, Democracy and the Internet.
"The Internet has changed that paradigm," she said. "It allows people to come find the candidate, rather than the candidate trying to pick the needles out of the haystack of people who would give them a small contribution."
However, Darr said those with lower incomes aren't as likely to donate online.
"Your online Internet audience is still very upper-middle class, highly educated," she said. "It's not the full spectrum of society that everybody hoped it would be with truck drivers and teachers and shopkeepers giving contributions. That still isn't the case."
Political watchers warn not to be fooled by the public appeals for small donations. Behind the scenes, they argue, campaigns are relying on backers with deep pockets and special interest groups to fill their '08 war chests.
"Big money is absolutely driving the race at this point," said Krumholz.
Campaign finance law dictates that supporters can give a candidate a maximum of $2,300 for the primary and up to another $2,300 for the general election.
In the first quarter, the Center for Responsive Politics found that the leading '08 candidates are relying mostly on those donors giving the maximum $2,300 contribution, not the smaller contributions.
"We've tracked the sources of the funds and it's largely the same as in past cycles," Krumholtz said. "You're going to see a lot of money coming from the finance, insurance and real estate sectors."
Romney is attracting large sums from wealthy private equity firms because of his days running Bain Capital.
McCain is also making the rounds on Wall Street, meeting privately with financial companies.
Clinton's biggest source of cash in the first quarter was the finance sector including private equity firms and hedge funds, followed by lobbyists.
"Seventy-four percent of Clinton's donors gave $2,300 or more, maxing out for the primary," said Krumholz. "Of those people, 48 percent have maxed out for both the primary and the general. They can no longer give, she's totally tapped them out," she said.
Only 9 percent of all Clinton's donors are giving less than $200, according to an analysis by the Center for Responsive Politics.
Clinton received huge sums in the first quarter from hedge funds like Blackstone, Avenue Capital and Farallon Capitol Management.
Meanwhile, Congress is considering a new proposal for ending a tax break allowing hedge funds and private equity fund operators to sidestep billions in income taxes.
The bill has left many of the senators running for president walking a political tightrope because of the donations they receive from hedge funds.
"Sen. Clinton believes there are broad concerns surrounding private equity in relation to the rest of the market," Clinton's press secretary told ABC News this week.
Edwards has had more success with small donors than Clinton. Fourteen percent of his donors in the first quarter have given $200 or less.
"But still, nearly 50 percent of his donors are giving $2,300, maxing out for the primary," said Krumholz.