Donald Trump, the billionaire businessman and GOP presidential frontrunner, has taken off the gloves in his fight with Texas Sen. [crscore]Ted Cruz[/crscore]. What was friendly jabbing in the Fox Business Channel debate has gotten nasty as Trump now directly questions Cruz’s eligibility to serve as president and the $1 million loan Cruz took from Goldman Sachs to jumpstart his Senate campaign.

[dcquiz] “Goldman Sachs owns him, he will do anything they demand. Not much of a reformer!” Trump tweeted.

“Ted Cruz purposely, and illegally, did not list on his personal disclosure form personally guaranteed loans from banks,” Trump added. “They own him!”

Trump is tying the citizenship accusation and the undisclosed loan question together. Trump is now floating the idea Cruz, who was born in Canada and a dual Canadian citizen until June of 2014, may have more undisclosed loans, possibly from Canadian banks. “Based on the fact that Ted Cruz was born in Canada and is therefore a “natural born Canadian,” did he borrow unreported loans from C banks?” Trump asked.

These latest salvos come amidst news that Cruz had another undisclosed 2012 campaign loan from Citibank. “Oh no, just reported that Ted Cruz didn’t report another loan, this one from Citi. Wow, no wonder banks do so well in the U.S. Senate,” Trump tweeted.

This latest attack comes as polls show the race between the two tightening in Iowa.

Ted Cruz was born in Canada and was a Canadian citizen until 15 months ago. Lawsuits have just been filed with more to follow. I told you so — Donald J. Trump (@realDonaldTrump) January 16, 2016

Ted Cruz said he "didn't know" that he was a Canadian Citizen. He also FORGOT to file his Goldman Sachs Million $ loan papers.Not believable — Donald J. Trump (@realDonaldTrump) January 16, 2016

Was there another loan that Ted Cruz FORGOT to file. Goldman Sachs owns him, he will do anything they demand. Not much of a reformer! — Donald J. Trump (@realDonaldTrump) January 16, 2016

The Ted Cruz wiseguy apology to the people of New York is a disgrace. Remember, his wife's employer, and his lender, is located there! — Donald J. Trump (@realDonaldTrump) January 16, 2016

Oh no, just reported that Ted Cruz didn't report another loan, this one from Citi. Wow, no wonder banks do so well in the U.S. Senate. — Donald J. Trump (@realDonaldTrump) January 16, 2016

Based on the fact that Ted Cruz was born in Canada and is therefore a "natural born Canadian," did he borrow unreported loans from C banks? — Donald J. Trump (@realDonaldTrump) January 16, 2016