WASHINGTON (AP) — Barack Obama was the first presidential candidate to raise more than $100 million in a month and in 2008 was the first to forgo public money for his campaign. Now, he faces the very real threat of being the first president to be outspent by a challenger.

Obama, who four years ago broke just about every fundraising record for a presidential hopeful, has now been forced to look his supporters in the eye and confess he might not keep pace with Republican Mitt Romney. It's a sobering realization for his campaign, which had imagined an unlimited budget for ads, offices and mail.

"I will be the first president in modern history to be outspent in his re-election campaign," Obama wrote to supporters recently.