The Illinois senator, the first serious black contender for the US presidency, has been seen as the main challenger to New York-based Ms Clinton in the race for the Democrat party's ticket.
But Ms Clinton's impressive campaign machinery and well-established fundraising ability had been expected to dwarf that of her main opponent.
Today's figures reveal that the gap between the two sides – in a period one year before the actual primary elections take place – is substantially less than was previously thought.
"I'm proud to tell you that, after the first quarter of the campaign, we've exceeded all of our hopes and expectations," the Washington Post newspaper quoted Mr Obama as saying in an email sent to supporters yesterday.
He described the total as a "measure of just how hungry people are to turn the page on this era of small and destructive politics and repair our American community."
Staff working on the Clinton campaign pointed out that their candidate has garnered the most funds in the party's history.
With such a wide-open field in both the Democrat and Republican primaries, the 2008 presidential election is expected to be the most expensive in the nation's history.
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