Sanders communications director Michael Briggs told The Washington Post that "it's been our best day ever."

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Sanders finished behind rival Hillary Clinton by a razor-thin margin of 0.2 points in the Iowa's Democratic caucuses Monday night. Clinton finished with 49.8 percent to Sanders's 49.6 percent.

Most of the money raised by Sanders is in the form of small online contributions, averaging about $27 each.

Sanders's campaign announced Sunday that it raised $20 million in January.

“The numbers we’ve seen since Jan. 1 put our campaign on pace to beat Secretary Clinton’s goal of $50 million in the first quarter of 2016,” Sanders's campaign manager Jeff Weaver said in a statement.

“Working Americans chipping in a few dollars each month are not only challenging but beating the greatest fundraising machine ever assembled.”