"He'll get up and he'll talk about his relationship with God, his relationship with the Bible, his relationship with all sorts of things and then he'll say Donald Trump loves Obamacare. It would've been dead if we had a different justice on the United States Supreme Court put there by him," Trump said, referring to conservative Chief Justice John Roberts, whose decisive 2012 vote upheld the controversial health care law.
"He's the one that got Justice Roberts onto the United States Supreme Court," Trump added.
While Cruz vocally supported Roberts' nomination at the time, he was not yet a U.S. senator and therefore could not vote to confirm Roberts to the Supreme Court.
The Cruz campaign did not immediately return with a request for comment.
Roberts' nomination passed before the Senate in 2005 and Cruz ascended to the legislative body more than seven years later.
Trump's jab at Cruz was just one of many the billionaire leveled at Cruz, who just two days earlier defeated Trump to win the Iowa caucuses.
But that win came after Cruz and his allies relentlessly knocked Trump, accusing him of supporting Obamacare.
"A vote for Donald Trump is a vote for Obamacare," Cruz said the day before the caucuses.
Meanwhile, a super PAC supporting Cruz and another opposing Trump ran attack ads tying Trump to President Barack Obama's signature health care law.
Trump said in a September interview that "everybody's got to be covered" and "the government's gonna pay for it" when asked if he supported universal health care. He also noted that it was an "un-Republican thing for me to say."
Still, Trump has repeatedly insisted that he will "repeal and replace Obamacare," which he said once again Wednesday night here to raucous applause.
Cruz, for his part, has slammed Roberts since the conservative chief justice ruled in favor of Obamacare -- despite praising Roberts when his nomination was up for consideration.
"As an individual, John Roberts is undoubtedly a principled conservative, as is the president who appointed him," Cruz wrote in 2005 in the National Review
. "As a jurist, Judge Roberts' approach will be that of his entire career: carefully, faithfully applying the Constitution and legal precedent."