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Trump began the morning by slamming Cruz in a series of tweets

Cruz, who once declined to attack Trump, shed any caution he may have had about laying into his top rival

Fort Mill, South Carolina CNN  — 

Ted Cruz and Donald Trump lashed into each other Saturday, with the Texas senator unloading on Trump’s record, temperament and fitness to be commander in chief. Meanwhile, Trump spent much of the day slamming his top GOP rival in a repeated Twitter spree so fierce – even for a candidate who is notable for taunting and insulting his opponents – it prompted prominent conservative commentator Mark Levin to publicly tell the real-estate mogul to back off.

The salvos – exchanged hours before both were scheduled to appear at a tea party event in South Carolina – mark another escalation between the two leading GOP candidates a little more than two weeks before the first votes are cast in Iowa. For Trump, Levin’s criticism was a rebuke from a wing of the Republican Party he needs in order to capture the Iowa caucuses, while Cruz’s comments represent his harshest attacks against a rival he once promised to “smother with love.”

Speaking to reporters, Cruz said “Donald’s record does not match what he says as a candidate.” He also aggressively ridiculed Trump’s obsession with the latest opinion surveys, saying that Trump’s early morning attacks on Twitter come because he is “dismayed” about a recent NBC News/Wall Street Journal poll showing a competitive race.

“I imagine it pulled him out of bed this morning and sent him tweeting and tweeting and tweeting,” he said. “I think in terms of a commander in chief, we ought to have someone who isn’t springing out of bed to tweet in a frantic response to the latest polls.”

Cruz referred repeatedly to an interview Trump did with NBC News’ Tim Russert 17 years ago, in which he defines his “New York values” as distinct from “Iowa values.” Cruz said those values – pro-abortion rights, including supporting partial birth abortion and pro-gay marriage – explained Trump’s worldview. And he dredged up the former Democrat’s donation history to some of the state’s leading politicians, including Hillary Clinton.

“Given the fact that for much of his life, Donald was financially supporting those politicians – writing checks to Hillary Clinton, writing checks to Andrew Cuomo – it is a fair inference that he supports their policies,” Cruz said.

The Texas senator, then asked for some differences on national security between him and Trump, offered that was unaware of what Trump’s foreign policy is.

“To be honest, I don’t know what Donald’s position is,” Cruz said.

Complementing Cruz’s attack was a tweet sent out by his campaign Saturday morning, embedding the 1999 Russert interview on “Meet the Press.”

Levin slams Trump over Twitter rampage

Trump began the morning slamming Cruz in a series of tweets, taking a break to appear at a campaign event in Portsmouth, New Hampshire, before resuming his tirade.

“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,” Trump tweeted shortly before 7 a.m. ET, referring to a lawsuit filed by a Houston man challenging the eligibility of Cruz, who was born in Canada to an American mother, to be president.

Then Trump slammed Cruz on not disclosing a Goldman Sachs loan, writing, “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” he said.

Trump then referenced a New York Times report from Friday that said Cruz failed to disclose a second loan from Citibank during his 2012 Senate run.

“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!”

Cruz declined to comment on the Times report when asked by a CNN reporter during an appearance in Columbia, South Carolina, on Friday.

Trump, however, wasn’t done. A few hours after his first Twitter rant, Trump resumed his assault in the afternoon to call Cruz a “hypocrite,” slamming him again on his undisclosed loans and seeking donations from people who support same-sex marriage.

“If Ted Cruz is so opposed to gay marriage, why did he accept money from people who espouse gay marriage?” he asked.

Trump also fired back against Cruz’s attacks on New York.

“Everybody that loves the people of New York, and all they have been thru, should get hypocrites like Ted Cruz out of politics!”

To further his defense of the Big Apple, he tweeted a photo of the destroyed World Trade Center days after 9/11.

Trump’s fury attracted the notice of Levin, a conservative writer, radio host and tea party favorite who took to Facebook Saturday afternoon to tell the GOP front-runner to “either cut the crap” or he “will lose lots and lots of conservatives.”

“Put down your computer keyboard for a few hours, think before you tweet, and collect yourself,” Levin said in the post. “I am already hearing more and more people getting fed up with the low road you’re taking against Cruz, which has obviously intensified this morning.”

Levin’s post also includes a link to a related Daily Caller story about Trump’s rant.

CNN’s Betsy Klein contributed to this report.