Ted Cruz failed to disclose a $500,000 Goldman Sachs loan that helped fund his 2012 Senate campaign

Sen. Ted Cruz (R-Texas), one of the leading candidates in the 2016 Republican presidential primary, might have some explaining to do, after questions about his 2012 Senate campaign surfaced on Wednesday.

According to a report from The New York Times, Cruz appears to have failed to completely disclose the source of some of the funding that helped boost his first Senate campaign - including a low-interest loan totaling up to $500,000 from Goldman Sachs.

The NYT's Mike McIntire writes Cruz initially reported that $960,000 of "personal funds" went into his 2012 Senate campaign. Additional money added two months later brought his campaign's total haul that year to $1.2 million.

It "was all we had saved," Cruz said to The Times years ago.

The Times reports that documents filed with the Senate in relation to Cruz's first campaign "does not find a liquidation of assets that would've accounted for all the money he spent on his campaign."

In 2012, according to the documents cited by The Times, Ted Cruz and his wife, Heidi reportedly obtained loans from Citibank and Goldman Sachs, totaling $750,000 - and eventually increasing to $1 million. Heidi Cruz works for Goldman Sachs.

The purpose of the loans were not mentioned at the time, and were not included in documents filed with the Federal Election Commission, The Times reports.

A spokeswoman for the Cruz's presidential campaign said the Goldman Sachs loan "was drawn against the value of the Cruzes brokerage account [and] was a source of money for the Senate race."

The spokeswoman said the failure to disclose the Goldman Sachs loan was "inadvertent."

Though Cruz has been rising in some primary polls of late, he's been hammered by his opponents in the race for the GOP presidential nomination. An all-out war broke out between Cruz and Donald Trump in recent days, in which Trump has been casting doubt on Cruz's eligibility to run for president.