Republican presidential candidate Ted Cruz is blasting rival Donald Trump for a National Enquirer story accusing Cruz of having five mistresses. Here's a breakdown of how a week of fighting got us here. (Sarah Parnass/The Washington Post)

OSHKOSH, Wis. – Sen. Ted Cruz (R-Tex.) blamed “Donald Trump and his henchmen” for planting a National Enquirer story that accused him of extramarital affairs. Vehemently denying the story as “garbage” and “complete and utter lies,” the Republican presidential hopeful took his longest step yet toward refusing to back Trump if he wins the party’s nomination.

“I don’t make a habit out of supporting people who attack my wife and attack my family,” said Cruz. “And Donald Trump is not going to be the Republican nominee.”

In recent days, the competition for the GOP nomination has taken a particularly nasty and personal turn. On Thursday, Cruz angrily denounced Trump after the Republican front-runner’s posted tweets  mocked the appearance of his wife, Heidi Cruz, and threatened to “spill the beans” about her.

On Friday, after a crowded rally at a parking cone factory here and after attacking Trump from the stage for his tweets, Cruz himself brought up the Enquirer's story that accused the senator of having had five mistresses – a subject some of the reporters covering him were loath to even raise. “It became clear as the campaign went on that Donald was a whole lot of sizzle without any substance,” said Cruz. “When he’s scared, when he’s losing, his first and natural resort is to go to sleaze and to go to slime.”

That was how Cruz introduced the subject of the Enquirer story, which alleged that the candidate had carried out affairs with five women – women whom bloggers and political activists were starting to “identify” as prominent political pundits. The story had bubbled up on social media, with the hashtag #TedCruzSexScandal appearing in tweets that asked reporters to follow the story.

The Washington Post has not been able to confirm any of the allegations made by the Enquirer.

Friday on CNN, a Trump supporter, Boston Herald columnist and radio host Adriana Cohen accused a former Cruz staffer, Amanda Carpenter, of being one of the five women cited in the Enquirer story. The Enquirer published photos of five women with their faces blurred and did not give their names.

Carpenter vigorously denied the allegation: “What’s out there is tabloid trash. If someone wants to comment on it, they can talk to my lawyer. It is categorically false. You should be ashamed for spreading this kind of smut,” she said. “I will not be intimidated. I will continue to make my thoughts known about Donald Trump, and I’m not backing down.”

Katrina Pierson, a Trump spokeswoman who once worked for Cruz, also said the story is false.

"Speaking for myself, the article is trash and 100% false," Pierson said in an email to The Post.

Trump, in a statement, said he had no idea whether the Enquirer story is true or not, but he denied having anything to do with it.

"I did not know about it, and have not, as yet, read it. Likewise, I have nothing to do with the National Enquirer and unlike Lyin’ Ted Cruz I do not surround myself with political hacks and henchman and then pretend total innocence," Trump said. "Ted Cruz’s problem with the National Enquirer is his and his alone, and while they were right about O.J. Simpson, John Edwards, and many others, I certainly hope they are not right about Lyin’ Ted Cruz. I look forward to spending the week in Wisconsin, winning the Republican nomination and ultimately the Presidency in order to Make America Great Again. "

Cruz blamed the story on Roger Stone, a longtime political adviser to Trump.

“It is a story that quoted one source on the record: Roger Stone, Donald Trump’s chief political adviser,” said Cruz. “It is attacking my family. And what is striking is Donald’s henchman, Roger Stone, had for months been foreshadowing that this attack was coming. It’s not surprising that Donald’s tweet occurs the day before the attack comes out. And I would note that Mr. Stone is a man who has 50 years of dirty tricks behind him. He’s a man for whom a term was coined for copulating with a rodent. Well, let me be clear: Donald Trump may be a rat, but I have no desire to copulate with him.”

The copulation reference was to a term coined to describe Stone and other political allies of Richard Nixon who spread rumors and foiled the campaign events of rivals.

Stone, who had promised a bombshell on Cruz, said, "This is why they call him Lyin' Ted."

"Dirty Tricks? Let's ask Ben Carson," Stone told The Post, referring to a rumor made about the other GOP rival dropping out of the race. "Most of what I know about this matter I learned from reporters at your newspaper."

Last August, Trump said he cut ties with Stone, saying he wanted to surround himself with "only the best people."

“I terminated Roger Stone last night because he no longer serves a useful function for my campaign,” Trump said. “I really don’t want publicity seekers who want to be on magazines or who are out for themselves. This campaign is not about them. It’s about victory and making America great again.”

Cruz also took the leaders of the Enquirer to task, saying they were in league with the Trump campaign.

“The CEO of the National Enquirer is an individual named David Pecker,” said Cruz. “Well, David is good friends with Donald Trump. In fact, the National Enquirer has endorsed Donald Trump, has said he must be president … [and] years from now, when my daughters google this, they will read these lies, these attacks that Donald and his henchmen, that his buddies at the National Enquirer spread about him.”

Cruz, who addressed the National Enquirer story for seven minutes, closed by analyzing “how a rumor gets spread.”

“They get their henchmen to put it out on the Internet,” he said. “Then they get the National Enquirer to report – not based on facts, not based on witnesses, but based on their reporting – that it’s on the Internet after they put it on the Internet. And I would note, another site, Gawker, which just had a $100 million judgment against them, then reports that the National Enquirer is reporting on these rumors, all of which started with Donald Trump.”

When Cruz opened the floor to questions, each was about the allegations. First, addressing the inevitable “pledge” to back Trump if he won, Cruz said he didn’t “make a habit” of supporting people who smeared his family. Then a local reporter seemed to irritate Cruz by asking if both he and Trump were “childish” and degrading the tone of the campaign.

“Sir, let’s be clear,” said Cruz. “One person has been childish, and that’s been Donald Trump.”

“I’m watching it every day,” said the reporter. “Both of you are going back and forth with this childish stuff.”

“Sir, I understand that the game the media wants to play is when Donald attacks my family to say that everyone is guilty,” said Cruz. “I have never attacked Donald’s family. I do not intend to. Indeed, when Donald sent a second tweet attacking my wife, I responded by saying ‘Donald, real men don’t attack women. Your wife is lovely.’ So not only did I not attack his wife, I praised his wife. Heidi is the love of my life. I’m sorry, sir, if you believe that defending your wife and defending your family is childish. But it is not.”

Cruz tried to wrestle the subject back to Trump’s refusal to debate him, accusing him of “hiding in Trump Tower” instead of campaigning in Wisconsin. (Indeed, on March 29, Trump will make his first public appearance of any kind since his March 21 speech to the American-Israeli Public Affairs Committee.)

“He sits in Trump Tower and sends tweets late at night,” said Cruz. “We need a president who is fighting for the people of America and not battling his personal demons on Twitter.”

Cruz turned and left the news conference, ignoring a shouted question that seemed to say everything about what Trump had done to the campaign’s tone.

“Senator Cruz, have you been faithful to your wife?”

Katie Zezima and Jose DelReal contributed to this report.