Will President Obama be the first billion-dollar man?

He raised and spent $750 million in the 2008 campaign, and there is already speculation that the cash-collection operation for his 2012 reelection bid will crest the once-unimaginable sum of $1 billion raised. (That's a one and nine zeros. Nine!)

"It's not unrealistic at all, given the amount raised and spent in 2008 and the amount Republican interest groups and 527s will spend against him," said a former Obama administration official.

A look at the trend line of fundraising for presidential candidates over the past several elections suggests a doubling effect every four years.

In 2008, Obama raised an eye-popping $745 million, while Sen. John McCain (R-Ariz.) collected $368 million. Total spending, including third-party candidates, amounted to $1.3 billion, according to the Center for Responsive Politics.

Four years earlier, President George W. Bush brought in $367 million while Sen. John Kerry (D-Mass.) collected $328 million. Total spending in 2004 was about half that of 2008's: $718 million.

The key difference between 2004 and 2008 was that Obama became the first person to opt out of public financing for the general election since the adoption of the current campaign finance system in the wake of the Watergate scandal.

Obama's decision - announced in June 2008 to much fanfare - proved close to decisive as his massive fundraising over the last five months of the campaign allowed him to overwhelm McCain on television in every swing state.

Given Obama's success after forgoing public financing in the 2008 general-election campaign, it's a virtual certainty that neither the president nor the Republican nominee will participate in that system for the 2012 general election.

Three other factors suggest that the idea of Obama as a billion-dollar candidate in 2012 is not so far-fetched.

First, he collected $750 million while running as a senator. He'll now be running as a president, which should allow him to clean up financially to an even greater extent, thanks to the power of incumbency.

Second, the continued development and maturation of Internet fundraising over the past four years means that the $500 million - yes, you read that right - that Obama raised online in 2008 could well be topped in 2012, noted Ben Ginsberg, a top Republican lawyer who served as an adviser to former Massachusetts governor Mitt Romney's 2008 presidential bid.

Third, the growth of a shadow Republican Party of outside groups - epitomized by American Crossroads, which spent $70 million on the 2010 midterms - should help fuel Democratic donations to Obama. (It remains unclear whether a Democratic-aligned outside group - or groups - will form to siphon off some of those donations.)

While the pieces are clearly in place for Obama to crest the $1 billion fundraising mark in 2012, some skepticism remains - even among his supporters - about the president's ability to reach that lofty mark.

One Obama fundraiser points to the difference between 2012 and 2008, when the absence of an incumbent candidate meant open primaries on both sides: "We will have very few events that drive online spikes, and the president probably won't do as many events as even Bush in 2003 and 2004."