Republican presidential candidate Ted Cruz reportedly failed to disclose a second bank loan of $500,000 for his 2012 Senate campaign, according to a letter he sent to the Federal Election Commission (FEC) on Thursday, raising questions not only about transparency, but also about the narrative of his political career.

The disclosure of the loan from Citibank comes after the Texas senator was already facing scrutiny for failing to properly report a loan from Goldman Sachs for $500,000 that was also used to fund his 2012 bid. The one-page letter, obtained by The New York Times, said both loans were "inadvertently omitted" from the required filings.

"Those loans have been disclosed over and over and over again on multiple filings," Cruz said on Wednesday, according to Politico. "If it was the case that they were not filed exactly as the FEC requires, then we'll amend the filings. But all of the information has been public and transparent for many years. And that's the end of that."

However, the disclosures also call into question the story that Cruz often cites in stump speeches about liquidating his family savings of $1 million to fund a scrappy, beats-all-odds campaign against a wealthy establishment opponent, a story that plays well among populist audiences.

In Thursday's GOP debate in South Carolina, Cruz, when asked about the loan, called it an "inadvertent" mistake and said that his campaign has reached out to the FEC to amend the filing.

"We took a loan against our assets to invest it in that campaign to defend ourselves against those attacks and the entire New York Times attack is that I disclosed that loan on one filing with the United States Senate," he said, ABC News reported. "That was a public filing, but it was not on a second filing with the FEC. Both of those filings were public. And yes, I made a paperwork error disclosing it on one piece of paper instead of the other. But if that is the best hit New York Times has got, they better go back to the well."