Donald TrumpDonald John TrumpDems flip Wisconsin state Senate seat Sessions: 'We should be like Canada' in how we take in immigrants GOP rep: 'Sheet metal and garbage' everywhere in Haiti MORE has intensified his feud with Ted CruzRafael (Ted) Edward CruzWith religious liberty memo, Trump made America free to be faithful again Interstate compacts aren't the right way to fix occupational licensing laws Texas Dem: ‘I don’t know what to believe’ about what Trump wants for wall MORE over the Republican presidential rival's wife after she slammed his statements for having "no basis in reality."

Trump shared an image on Twitter around midnight Wednesday comparing his wife, Melania, a former model, to Cruz's wife, stating, "A picture is worth a thousand words."

Cruz delivered a fiery denunciation of Trump Thursday afternoon for dragging his wife into the center of the race.

"It's not easy to tick me off. I don't get angry often. But you mess with my wife, you mess with my kids, that'll do it every time," Cruz said in Wisconsin.

"Donald, you're a sniveling coward. Leave Heidi the hell alone."

The retweet from Trump set off a firestorm, drawing a one-word response from another woman who has feuded publicly with the billionaire.

"Seriously?" Fox News anchor Megyn Kelly tweeted.

CNN’s Kate Bolduan sparred with a Trump adviser over the tweet during an interview Thursday, calling it “demeaning to women.”

“As a woman, it’s demeaning to not only Ted Cruz’s wife, it’s demeaning to Melania Trump because she has a lot more going for her than just her looks, and you don’t see that in this retweet,” Bolduan said to Stephen Miller, a senior Trump adviser, during her show “At This Hour.”

Bolduan peppered Miller with questions about why he thinks that behavior is appropriate for a presidential candidate.

Miller stood by his boss’s decision to share the image. “I think the retweet speaks for itself,” he said. “Of course I endorse the decision to retweet it.”

Trump first raised the specter of a fight with Ted Cruz with a tweet Tuesday night, amid primary voting in Arizona and Utah, by threatening to "spill the beans" on his rival's wife.

He cited an ad from an anti-Trump super-PAC running that featured his wife posing nude, claiming it was from Cruz. The Texan says he has no connection to the group that ran the ad.

Miller on Thursday said the Cruz campaign should tell the super-PAC to remove the Melania Trump ad.

Cruz has knocked Trump in a series of interviews, saying the threat to go after his wife "should be beneath Donald" and suggesting it illustrates the businessman's character.

Heidi Cruz has spoken out as well.

“Most of the things Donald Trump says have no basis in reality,” she told reporters during a campaign stop Wednesday in Wisconsin, acknowledging Trump's threat to go after her publicly.

The feuding comes at a time when Trump is more than halfway to locking up the GOP nomination. Cruz is fighting to thwart his path to the required 1,237 delegates, which could force a contested convention in July to determine the nominee.

The next big state in the GOP race is Wisconsin, which will hold a primary on April 5. Trump and Cruz appear to be locked in a virtual tie in the state, which will award 42 delegates.

Sen. Lindsey GrahamLindsey Olin GrahamDHS chief takes heat over Trump furor Overnight Defense: GOP chair blames Dems for defense budget holdup | FDA, Pentagon to speed approval of battlefield drugs | Mattis calls North Korea situation 'sobering' Bipartisan group to introduce DACA bill in House MORE (R-S.C.), a former presidential candidate who is now supporting Cruz, urged the candidates to back away from the fight over their wives and return to more pressing issues.

“It's a good year to be single," Graham quipped during an interview Thursday on NBC's "Today" show.

“The bottom line is, when you think it can't get worse ... hey guys, knock it off. The world is falling apart. Man up. You've got great wives and great families," Graham said.

—This story was updated at 4:28 p.m