"Ted Cruz may not be a U.S. citizen, right? But he's an anchor baby. No, he's an anchor baby -- Ted Cruz is an anchor baby in Canada," Trump quipped in a speech to supporters in Nashua, New Hampshire.
Trump's use of the term -- which describes children born on U.S. soil to parents who are in the country illegally and is widely considered to be derogatory -- marks the latest escalation of his attacks against Cruz in which he highlights the Texas senator's Canadian birthplace.
Cruz was born in Canada to a Cuban father and an American mother, who were both living legally in Canada at the time, making him an American citizen by birth.
Cruz spokeswoman Catherine Frazier hit back at Trump in a statement Friday, knocking the New York billionaire's past support for legal abortion and praiseworthy comments about former Secretary of State Hillary Clinton.
"The only anchor here is the one being dragged behind the SS New York Values, causing Donald Trump's campaign to stall out as voters learn about his affinity for Hillary Clinton and his previous statements supporting abortion," Frazier said in a statement to CNN.
Trump has raised the issue of "anchor babies" in the United States more than any other candidate, regularly suggesting in his stump speeches that children born on U.S. soil to undocumented parents should not be U.S. citizens, as they are today considered under the law.
The GOP front-runner also has repeatedly raised Cruz's Canadian birth to suggest that Cruz may not be eligible to serve as president of the United States. Trump and a handful of legal scholars have suggested the Constitution's "natural-born citizen" requirement requires the president be born on U.S. soil, and the issue has never been adjudicated in federal court.
Trump also knocked Cruz's debate performance, saying that the Texan "got really pummeled" by the rest of the field.
"Actually, I'm glad I wasn't there 'cause I guess all of that -- he got pummeled, wow," Trump said. "And you know they didn't even mention he was born in Canada."
"He got beaten up pretty badly last night," Trump added.
Trump decided to boycott the debate after feuding with Fox News over one of the debate's moderators, Megyn Kelly, and after the network issued a statement mocking Trump.
Trump instead hosted an event Thursday night in Iowa to raise money for veterans' causes, raking in about $6 million, including a $1 million donation of his own, for 22 veterans organizations, the campaign said.
Trump noted that skipping the debate was a "risk" given that other candidates could have shifted the dynamic of the race in Trump's absence.
But Trump said his competing event was "a 10" and suggested he would get a boost in the polls as a result of his bold decision.