As Ted Cruz tells it, the story of how he financed his upstart campaign for the U.S. Senate four years ago is an endearing example of loyalty and shared sacrifice between a married couple.

“Sweetheart, I’d like us to liquidate our entire net worth, liquid net worth, and put it into the campaign,” he says he told his wife, Heidi, who agreed.

But the couple’s decision to pump more than $1 million into Cruz’s successful Tea Party-darling Senate bid in Texas was made easier by a large loan from Goldman Sachs, where Heidi Cruz works. That loan was not disclosed in campaign finance reports.

Those reports show that in the critical weeks before the May 2012 Republican primary, Cruz — currently a leading contender for his party’s presidential nomination — put “personal funds” totaling $960,000 into his Senate campaign. Two months later, shortly before a scheduled runoff election, he added more, bringing the total to $1.2 million — “which is all we had saved,” as Cruz told the New York Times several years ago.

A review of personal financial disclosures that Cruz filed later with the Senate does not find a liquidation of assets that would have accounted for all the money he spent on his campaign. What it does show, however, is that in the first half of 2012, Ted and Heidi Cruz obtained the low-interest loan from Goldman Sachs, as well as another one from Citibank. The loans totaled as much as $750,000 and eventually increased to a maximum of $1 million before being paid down later that year.

Neither loan appears in reports the Ted Cruz for Senate Committee filed with the Federal Election Commission, in which candidates are required to disclose the source of money they borrow to finance their campaigns.

A spokeswoman for Cruz’s presidential campaign, Catherine Frazier, acknowledged that the loan from Goldman Sachs, drawn against the value of the Cruzes’ brokerage account, was a source of money for the Senate race. The failure to report the Goldman Sachs loan, for as much as $500,000, was “inadvertent,” she said, adding that the campaign would file corrected reports as necessary.

Kenneth A. Gross, a former election commission lawyer, said that listing a bank loan in an annual Senate ethics report would not satisfy the requirement that it be promptly disclosed to election officials during a campaign.

“They’re two different reporting regimes,” he said. “The law says if you get a loan for the purpose of funding a campaign, you have to show the original source of the loan, the terms of the loan and you even have to provide a copy of the loan document to the Federal Election Commission.”

There would have been nothing improper about Cruz obtaining bank loans for his campaign, as long as they were disclosed. But such a disclosure might have conveyed the wrong impression for his candidacy. Cruz was campaigning as a populist firebrand who criticized Wall Street bailouts and the influence of big banks in Washington.