CHARLESTON, S.C. — It didn't stay in Vegas.

After making his debate stage debut as a top-tier contender last month in Sin City, U.S. Sen. Ted Cruz is again heading into a debate with a growing target on his back — and navigating fresh tension in his relationship with billionaire Donald Trump. 

The GOP's sixth debate, its first of 2016, will mark the field's smallest gathering yet — just seven candidates made the cut for the prime time event— and with less than three weeks until the first nominating contests begin, there could be a new urgency to weaken the Texan.

"I think Cruz is going to be under more pressure ... than he has been at any time because he's a real threat now," said Matt Mackowiak, an Austin-based Republican strategist. "There's a chance Cruz is going to be on defense a lot."

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Since the last debate, Cruz has only become more scrutinized by his GOP rivals, ranging from the national pack leader Trump to long-shot foes such as former U.S. Sen. Rick Santorum of Pennsylvania. Since Christmas, Cruz has largely avoided getting too tripped up by the onslaught, but there are signs it is taking a toll on him in Iowa, the first-in-the-country caucus state where he emerged last month as a frontrunner.

Among the more recent developments Cruz may have to contend with Thursday night is a report that he did not properly disclose a loan from his wife's employer, Goldman Sachs, during his 2012 Senate run. Reacting to the New York Times story Wednesday night, Cruz downplayed the issue as a "technical and inadvertent filing error" that he was working to resolve.

The revelation nonetheless provides an opening for Cruz's opponents to claim he was seeking the assistance of Wall Street banks while railing against them on the stump. 

“I don’t think it’s really all that strong an argument," said Mark Jones, a political science professor at Rice University. "All he did was borrow against assets he already had, which is a very common device."

"Predictably everyone on that stage is very wealthy and I’m sure every one on that stage has at one point used that. Maybe not Marco Rubio," added Jones, referring to Cruz's GOP rival whose financial troubles have been well known.

Regardless of whether the loan issue comes up, Cruz is almost guaranteed to mix it up with his Senate colleague from Florida. The two have been warring over immigration and foreign policy for weeks, and Rubio has more recently pounced on a part of Cruz's tax plan as antithetical to conservative values. 

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But just like it did in Las Vegas, the attention Thursday night will be on a Cruz-Trump relationship that seems increasingly on the rocks, especially as the billionaire stokes questions about the senator's eligibility to be president due to his Canadian birth. The billionaire has reportedly said he will not raise the issue Thursday night, though that leaves on the table other lines of attack Trump has honed against Cruz, including his stance against ethanol mandates and subsidies as well as his rocky tenure in the Senate.

In recent days, Cruz has taken a sharper tone toward Trump than ever, suggesting he is too cozy with Democrats, implying he is a weak candidate for the general election and saying he represents "New York values" — not those of Iowa, for example. Cruz swiped at Trump again when asked Wednesday night about the billionaire's persistent questions about his citizenship.

"You know, it's very interesting. This issue did not seem to concern Donald until a little over a week ago, when suddenly he was trailing in the polls in Iowa," Cruz told reporters after a rally in Dorchester, South Carolina. 

It would not be the first time a showdown between Cruz and Trump appeared brewing with a debate looming. In the lead-up to their last meeting, which was held Dec. 15 in Las Vegas, the two seemed more likely than ever to clash, only for Trump to flatly take a pass on an opportunity to criticize Cruz — and later insist they had buried the hatchet. 

At the end of the day, Mackowiak said, Cruz and Trump still have plenty of disincentive to tangle with one another: Trump because debates, with their emphasis on substance over sound bites, are not his strong suit and Cruz because he needs to avoid alienating the many Trump supporters who count him as their second choice.

That does not mean the stakes are not high for either candidate, according to the Republican strategist. The GOP hopefuls will have one last chance to make their cases to Iowans from the debate stage when they meet again Jan. 28 in Des Moines.

"I think this debate's going to matter, and it's going to basically freeze the race for two weeks," Mackowiak said of the South Carolina event. "You're getting into decision time for a lot of these caucus goers."

Cruz, known to lay low the day of debates, is again hunkering down Thursday. Following the debate, he is set to resume a four-day swing through South Carolina, with stops Friday in Columbia and North Greenville then Saturday in Fort Mill and Myrtle Beach.

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