The Romney campaign says that $9 million of the $20 million loan has been paid back already, and with $168.5 million in the bank at the end of August, the Republican hopeful should not struggle to pay off the remainder of the debt.

The loan was necessary because individual donors can give a maximum of just $2,500 to primary campaigns, but can give significantly more to a joint fundraising account with the Republican National Committee and his general-election fund — money not available until after a candidate officially accepts the nomination. Since Romney's fundraising strategy has focused on big donors writing large checks, much of the impressive fundraising totals Romney posted through the summer remained unavailable.

While the loan seems mostly an accounting trick to avoid restrictions on spending general-election funds early, there is a possibility Democrats could seize on the news. Earlier this month, Romney saw a record $111.6 million fundraising haul eclipsed by a $114 million intake by the Obama campaign.