Donald Trump has furiously reacted to a conservative super PAC backing Ted Cruz which used an advert slut-shaming his wife Melania.

The ad, circulated on social media, shows the former model in a nude 2000 GQ photo shoot with the words: 'Meet Melania Trump, your next First Lady. Or you could vote for Ted Cruz on Tuesday.'

But just before results started to trickle in, Mr Trump responded to the ad in characteristic bombastic fashion on Twitter.

'Lyin' Ted Cruz just used a picture of Melania from a G.Q. shoot in his ad. Be careful, Lyin' Ted, or I will spill the beans on your wife!', he wrote.

Cruz for his part, was quick to respond, saying: 'Pic of your wife nor from us. Donald, if you try to attack Heidi, you're more of a coward than I thought. #classless.'

The super PAC Make America Awesome, which describes itself as an independent group focused on 'unconventional and cost-effective tactics' created this ad attacking Donald Trump through his wife Melania (pictured, in a GQ photo shoot in 2000)

Furious: Trump hit out at Ted Cruz for the advert, saying he would 'spill the beans' on his wife Heidi Cruz. It was unclear exactly what he meant although she has a history of depression

Careful Donald: Cruz quickly responded, saying if he tried to attack Heidi, he would be 'more of a coward than I thought'. He also called it 'classless'

Ted Cruz and wife Heidi wave to supporters during a campaign stop earlier this month in Concord, NC

Founder of the PAC, Republican Liz Mair, told Buzzfeed the ads are expected to reach 10,000 Mormons a day. The religious group is known to dislike Trump (pictured with Melania)

It was unclear what exactly he was refering to regarding Ted's wife Heidi Cruz, although it is well documented she suffered from depression 10 years ago, culminating in an incident in 2005 when cops found her with her heads in her hands beside a Texas expressway. A police report said she was a 'danger to herself'.

Cruz, who has a precarious 50.1per cent polling average, needs to win a majority backing in order to take all 40 of Utah's delegates.

Republican strategist Liz Mair, who founded the super PAC Make America Awesome, told Buzzfeed the ads have been targeting Mormons, who have been shown in previous election results to dislike the Donald.

While Trump is already expected to lose the Utah caucuses with just 11.9per cent of the vote, the PAC is hoping to tip the majority in favor of Ted Cruz, whose backing is on a knife's edge with 50.1per cent polling average.

If he fails to win the majority in Utah, the delegates will be split proportionally among the three candidates, diminishing Cruz's chances to top Trump, who is projected to take Arizona.

The Make America Awesome campaign also includes an ad highlighting Romney, a devout Mormon, and his public condemnation of Trump.

A third ad quotes the Donald on his previous pro-choice stance, although the candidate has now flip-flopped in the abortion debate and declared himself pro-life.

Mair told Buzzfeed the online campaign, which is the group's first endorsement of a specific candidate, is expected to reach 10,000 Mormons a day.

She also said the Melania ad will be promoted on Instagram specifically targeting LDS women.

HEIDI CRUZ'S BATTLE WITH DEPRESSION A 2005 police report that was uncovered last year details an incident where Heidi Cruz was taken in by a police officer after she was found sitting just feet away from a major roadway in Austin, Texas. On August 22, Cruz left her home shortly after 10pm and walked for miles before sitting down by the MoPac Expressway. Officer Joel Davidson was dispatched after reports came in of a woman sitting dangerously close to the side of the road with her head in her hands. When Davidson arrived on the scene Cruz identified herself and revealed she was not on any medication and had just two sips of a margarita that night, something Davidson confirmed saying she was not intoxicated at the time. Davidson 'believed she was a danger to herself' and eventually Cruz left with him in his patrol car. At the time, Cruz had recently left her job working for National Security Advisor Condoleezza Rice to be with her husband, who was serving as Solicitor General. Cruz had been commuting between Washington DC and Texas for an entire year as the couple's jobs kept them 1,500 miles apart. She had also just begun a new job working at Goldman Sachs as a private wealth manager. After the police report was released, an advisor to Senator Cruz put out statement saying; 'About a decade ago, when Mrs. Cruz returned from D.C. to Texas and faced a significant professional transition, she experienced a brief bout of depression. 'Like millions of Americans, she came through that struggle with prayer, Christian counseling, and the love and support of her husband and family.' Advertisement

Election results in Wyoming and Idaho, where there are significant Mormon populations, show the religious group favoring Cruz and Kasich over Trump.

History professor Matt Bowman told ThinkProgress.com that Mormons, who have historically experienced religious persecution, dislike the Republican frontrunner for his Islamophobic comments.

He added: 'Mormons place a high premium on being nice, and Trump is not nice.'

Make America Awesome is described on its website as 'a SuperPAC dedicated to blocking and reversing Donald Trump’s political ascent.

'We are an independent group, and are not authorized by any presidential candidate or candidate committee. Our focus is on using unconventional and cost-effective tactics, as opposed to stereotypical high-cost, limited-yield methods with the objective of providing maximum donor value.'

In reference to an anti-Trump ad they ran in January criticizing his business methods, the super PAC tweeted: '...If Trump’s opponents are serious about defeating him, they need to start running attacks that work with his voters now...'

The Make America Awesome campaign also includes an ad highlighting Romney, a devout Mormon, and his public condemnation of Trump

A third ad quotes the Donald on his previous pro-choice stance, although the candidate has now flip-flopped in the abortion debate and declared himself pro-life

But the photo slut-shaming Melania has raised a number of eyebrows across the political spectrum.

In an article on Mic.com, Anna Swartz wrote there were plenty of other reasons to attack the Republican frontrunner, from his 'racist tirades' to his 'extreme anti-immigration rhetoric'.

Others defended Melania and pointed out the fact that she is fluent in five languages and studied architecture and design before working as a model and running her own businesses.

Conservative news websites have also called the ad 'despicable' while others have pointed out the PAC's strategies could very well backfire.

Both Democrats and Republicans are voting in the Utah caucus and Arizona primary tonight. The Democrats will be voting in the Idaho caucus.