Cruz calls Trump "sniveling coward" and says "leave Heidi the hell alone"

Defending his wife, Republican presidential candidate Ted Cruz is telling Donald Trump to lay off Heidi Cruz, who the billionaire businessman attacked on Twitter earlier this week.

"It's not easy to tick me off," Cruz told reporters Thursday while on a tour of a Wisconsin manufacturing plant. "I don't get angry often. But you mess with my wife, you mess with my kids -- that'll do it every time. Donald, you're a sniveling coward and leave Heidi the hell alone."

The Texas senator's biting words come less than a day after Trump tweeted about Heidi Cruz's appearance.

On Thursday, the GOP front-runner reposted a tweet with photos comparing his own wife, Melania Trump, with Heidi Cruz. The caption read: "The images are worth a thousand words."

Since then, Trump's campaign has defended the tweet.

In an appearance late Wednesday on CNN, Trump spokesperson Stephen Miller said the New York businessman "responded as any normal person would" to what they believed was a "vicious, mean-spirited, uncalled-for attack on Mr. Trump's wife."

Miller had been referring to an attack ad -- launched by an anti-Trump super PAC in Utah the day of the state's nominating caucuses earlier this week -- that featured a risque photo of Melania Trump. The billionaire believed Cruz was behind the ads, though the unaffiliated "Make America Awesome Again" PAC claimed responsibility. On Twitter, Trump threatened to "spill the beans" about Cruz's wife in retaliation.

The Texas senator condemned Trump's reactions as the work of a "big, loud New York bully."

"Donald has a very unfortunate habit. When he gets scared, he lashes out," Cruz said Thursday. "And he insults and attacks whoever is standing near him."

Cruz further speculated that "Donald does seem to have an issue with women...Donald doesn't like strong women. Strong women scare Donald."

"Real men don't try to bully women," he added. "That's not an action of strength. That's an action of weakness. That's an action of fear. That's an action of a small and petty man who is intimidated by strong women. Real men don't do that. "