A campaign finance study published Wednesday reveals a pretty big difference between the campaigns of President Barack Obama and likely Republican challenger Mitt Romney: namely, 48 percent of Obama's money came from small donations.

That's not the case for the former Massachusetts governor, who's far and away the favorite candidate of employees and PACs in the financial industry: he raised just 9 percent of his campaign funds from small donors, the study found.

The Campaign Finance Institute (CFI) noted that Obama's 48 percent from small donors is actually outpacing his initial run for the presidency. By the end of 2007, the group noted, just 22 percent of Obama's $96.7 million in campaign funds came from small donors.

That's a stark contrast to the end of 2011, which saw 48 percent of Obama's reelection campaign's funds come from people giving $200 or less.

Romney, on the other hand, turned in about the same percentage of small donor contributions in his first run for the presidency -- just 9 percent, whereas two-thirds of his campaign's finances come from contributions of $2,500, the maximum one can give directly to a candidate. The CFI noted that another 15 percent of Romney's cash on hand came from donations between $1,000 - $2,499, which was virtually identical to his percentages in 2007.

In addition to finding most of his support from people with enough money to give large sums, Romney-supporting super PACs have spent the most money supporting his fight for the Republican nomination. Just one outside group, Restore Out Future super PAC, spent nearly $18 million to attack Romney's opponents, according to Federal Election Commission (FEC) records examined by The New York Times.

That super PAC is largely funded by billionaires, executives, hedge fund managers and others in the world of private equity, including the heirs to the Wal-Mart fortune.

President Obama, by contrast, has only just this week embraced the super PAC campaign model and endorsed a group supporting his reelection, explaining that if he did not, his campaign risked being overwhelmed by a torrent of money behind whomever ends up as the Republican nominee. He's since called for a constitutional amendment to ban unlimited private spending on political advocacy.

Despite appearances of big money getting cozy with Romney, recent FEC filings showed Obama with a commanding fundraising lead over his likely opponent, with $139.5 million versus Romney's $57.1 million.

He was also leading in opinion metrics: a recent average of presidential polling found Obama beating Romney by nearly 4 percent, but that number that could change dramatically as the election nears.