From an attorney who used to work at the FEC & practices campaign finance law…
“It is not uncommon for candidates not to realize that they have to report the source of lines of credit or loans to themselves on their FEC forms. That is, a candidate who takes out a personal loan against him or her self would not necessarily understand that it should be included on an FEC report.
“In short, candidates are able to contribute their own money without any dollar limit to their own campaign. Many people assume a personal loan is their own money, therefore they treat it as they would a contribution from their personal savings without realizing that a complicated provision of campaign finance law requires candidates to also report the source of such personal loans, even though they are made to the candidate and not their campaign committee. Media are making a big deal about a technical reporting problem that is not unique to Cruz.”