Sam Stein has the story.
Several Republican sources tell The Huffington Post that the former Minnesota governor was confronted by a far more intractable obstacle than leapfrogging the first two finishers -- Minnesota Rep. Michele Bachmann and Texas Rep. Ron Paul -- or facing the newest entrant to the field, Texas Gov. Rick Perry. Pawlenty, the sources say, was out of cash, his campaign having spent heavily in the lead-up to Ames, hoping for a better score than what he got.
.... One source suggested the campaign's debt was as high as $500,000, but another source with closer knowledge of the campaign deemed that figure far exaggerated.