NORTH CHARLESTON, S.C. — Don't expect Ted Cruz's fresh assault on presidential rival Donald Trump to abate anytime soon.

The Texas senator didn't unload on Trump during this week's Republican debate simply to undermine the celebrity businessman's suggestion that he is constitutionally ineligible for the presidency, although it was a factor. Rather, Cruz's attack on Trump's liberal "New York values" was the beginning of a two-prong strategy to kneecap the billionaire in Iowa and discard other competitors by framing the primary as a two-man contest between him and Trump.

"This is really coming down to a two-horse race between Donald Trump and Ted Cruz," Cruz campaign national chairman Chad Sweet told the Washington Examiner on Thursday, immediately following the first prime time debate of 2016. "Even though both Trump and Cruz are strong, one's got a much more consistent track record on all the major issues that conservatives care about."

Since November, Cruz and Trump have been tied for first place in Iowa and far ahead of the rest of the GOP field. That has led to high expectations; for Cruz because his path to the nomination is built around a strong showing in Iowa, for Trump because he's constantly bragging that he's winning in all the polls. A loss could be debilitating, winning generates momentum for the states that vote after the Feb. 1 caucuses.

That explains why Trump is smearing Cruz with the same "birther" conspiracy that he leveled against President Obama four years ago, and why Cruz abandoned a detente with the reality television star that he had nurtured assiduously for seven months. Indeed, the Cruz campaign always anticipated the end of its informal alliance with Trump. When the time came, the plan was to contrast Cruz's staunch conservatism with Trump's ideological flexibility and liberal past.

Cruz and Trump are both competing for the support of evangelicals, Tea Party voters and self-identified "very" conservative Iowa Republicans. The Cruz campaign is convinced that a contrast with Trump on issues and governing philosophy will give him the edge. That's why Cruz isn't abandoning his "New York values" charge, even after Trump scored points in the debate when he rebutted the Texan's criticism by raising the specter of the Sept. 11, 2001 terrorist attacks.

"I have heard their demands and I am happy to give them an apology. I apologize to the millions of New Yorkers that have been abandoned by liberal politicians," Cruz said Friday during a radio interview. "I apologize to all the pro-life, pro-marriage, pro-2nd Amendment New Yorkers who Gov. Cuomo brazenly told have no place in the state of New York because that's not who New Yorkers are."

Sweet delivered an even sharper rejoinder.

He conceded that Trump had a touching moment during the debate when he likened New York values to the strength and resolve the city showed in the aftermath of the deadly Sept. 11 attacks on the World Trade Center. But Sweet said the critique on Trump's values is legitimate, and suggested that the real estate mogul grow a stiffer spine, considering that he's one of the biggest attack dogs on the campaign trail.

"It's a rare contrast to see [Trump] be compassionate in invoking 9/11," Cruz's campaign chairman said. "But it doesn't address the fundamental thing that the senator raised. What that tells you is, he doesn't want to tangle with the senator, actually, on what he's raising. If you look at Donald Trump, he has had a pattern of insulting many different groups. But for some reason, when New Yorkers get insulted, he's the first to cry out. I come from the South, and we say, 'If you can't stand the heat, get out of the kitchen.'"

"If Donald wants a fight, it probably wouldn't be advisable of him to take us on in Iowa," Sweet added.

Cruz has a lot riding on Iowa. But he's not running a one-state campaign. He's well organized in all four early primary states, plus the Southern and Midwestern states that dominate the calendar in March. Engaging with Trump now, as voters begin to pay more attention and solidify their choices, is meant to eliminate others —besides the New Yorker — that could stand in his way beyond Iowa.

The Cruz camp believes the image of Cruz and the months-long national frontrunner going to toe-to-toe will elevate the Texan's stature and siphon votes from others if they can manage to convince voters that the senator is the only viable alternative to a candidate that isn't all that conservative, or Republican, to begin with. It's not necessarily a bad approach, some GOP strategists say.

"You are defined by the conflict you seek or conflict you avoid. You always want to be in the heavy weight round," said Stuart Stevens, who advised Republican nominee Mitt Romney four years ago. "The very first ad that Romney aired in 2012 took on Obama. Why? Because we wanted the conflict and we wanted to be in the heavy weight round."