Ted Cruz was being loudly cheered by many of the delegates at the Republican National Convention on July 20 – until he urged voters to "vote their conscience." (Peter Stevenson,Sarah Parnass,Jorge Ribas,Alice Li,Dalton Bennett/The Washington Post)

Sen. Ted Cruz’s pointed refusal to endorse Donald Trump during his prime-time address here at the Republican National Convention has reopened wounds from the hard-fought GOP primary, threatening further divisions in a party already struggling to unite behind their nominee.

During a contentious breakfast here Thursday morning with the Texas delegation — some in the group booed and heckled their senator — Cruz delivered a lengthy defense of his exhortation to Republicans the night before to “vote your conscience.” He said the party needs to “stand for shared principles” if Republicans want to win in November, but he also vowed not to speak negatively about Trump.

“In that speech last night I did not say a single negative word about Donald Trump,” Cruz said. “And I’ll tell you this morning, and going forward, I don’t intend to say negative things about Donald Trump.”

But some at the breakfast had some negative things to say about Cruz. A man held up a sign reading “Clinton/Cruz 2020.” Others yelled at him to sit down or accused him of sowing discord and reneging on promises.

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Cruz justified his remarks by saying that he congratulated Trump on securing the nomination. He also assured attendees that he will not be voting for Clinton in the fall. But he was far from conciliatory, repeating that although he would listen to Trump’s speech Thursday, he would not be endorsing the real estate mogul.

“I’m going to be listening to how he and the campaign conduct themselves every day from now until November,” Cruz said.

He also stood by his decision not to honor a pledge he made last year to support the eventual GOP nominee, saying that the pledge was rendered moot because Trump attacked his family.

“The day that was abrogated was the day this became personal,” he said. “I’m not going to get into criticizing or attacking Donald Trump, but I’ll just give you this response: I am not in the habit of supporting people who attack my wife and attack my father.”

Cruz asserted that he is not going to “act like a servile puppy dog” and thank Trump for taunting his family. A man yelled at Cruz to get over it because it’s all politics.

“No, this is not politics,” Cruz said. “I will tell the truth.”

Cruz said his speech Wednesday night was a blueprint for what he believes Republicans need to do to win in November — talk about things such as conservatism and issues such as immigration and terrorism. If “the dominant word is ‘Trump’ or of the dominant word is ‘Hillary’ or ‘email server,’ we’re going to lose.”

He swiped at the Trump supporters who booed him Wednesday night after he urged people to vote their conscience: “What does it say when you stand up and say, ‘Vote your conscience,’ and rabid supporters of our nominee begin screaming, ‘What a horrible thing to say?’ ”

Cruz campaign manager Jeff Roe left the door open for Cruz to endorse Trump in the future.

“We would love and would pray that we get to a position where we could support Donald Trump,” Roe said. But Trump will have to earn it, he said.

Cruz’s remarks Thursday morning also sowed discord within the Texas delegation, with members yelling at one another.

“If he said that about your wife or your dad, I hope you’d do the same thing. I hope you’d have some character,” Steve Toth said to fellow delegate Thomas Mathis as they verbally jousted.

Trump campaign chairman Paul Manafort said early Thursday that he and the campaign were disappointed with Cruz’s speech.

“Cruz used very bad judgment. I think he made a mistake,” Manafort said on NBC’s “Today” show Thursday. “I think he was not respectful to the invitation by the convention to come and speak. He understood what the responsibilities are of somebody in his position, and he didn’t meet them.”

Asked about Cruz’s remarks, Indiana Gov. Mike Pence — Trump’s running mate — said Thursday morning on Fox News that he was grateful Cruz delivered a speech but added that he did not hear it in its entirety .

“This was a tough and challenging primary,” Pence said. “These were tough competitors. And I’ve been through a few tough elections myself, and I know that those feelings can be strong.”

But Pence said he believes the party is “coming together” ahead of a tough general election against presumptive Democratic nominee Hillary Clinton.

“There’s always going to be differences and nuances in the way people express that,” Pence said. “But what I sensed in that hall the last several days, and especially last night, is a Republican Party that is coming together around the stakes of this election.”

Others were less diplomatic.

Former Arkansas governor Mike Huckabee tore into Cruz in a Facebook post after the speech, accusing the senator from Texas of betraying Trump’s trust.

“From where I sit, I didn’t see a statesman step forth for the country’s future,” Huckabee wrote.

“I saw a self-absorbed politician grab the microphone and try to line up his own future. Ted walked in tall and walked out small,” he wrote. “Trump trusted Ted and was rewarded with a betrayal.”

Reality-television star Phil Robertson chastised Cruz in an interview Thursday for his refusal to endorse Trump, even though the “Duck Dynasty” star had endorsed Cruz in the GOP primaries.

“I was behind Cruz,” Robertson said. “He lost. I lost. Now he’s out. Once you do that, you need to swallow your pride. The people said: ‘This is the one we want. We don’t want Cruz. We want this one.’ You need to get behind him.”

Even some of the staunchest anti-Trump Republicans at the convention have suggested that Cruz could have chosen his words more carefully.

“He hasn’t been here,” former Virginia attorney general Ken Cuccinelli II said. “So he doesn’t know the word ‘conscience’ has become kind of a buzzword this week in the rules. And I’m a rules person, as you may have noticed. It’s the first speech I wish I’d been able to vet, because I think we could have easily improved it for the audience in the room.”

Cruz was jeered off the stage Wednesday night as Trump, with his characteristic showman’s instincts, entered the hall and gave a thumbs-up.

The showdown between two of the GOP’s most abrasive personalities was evidence that many party stalwarts have not reconciled themselves to the fact that the celebrity billionaire who vanquished 16 opponents in the primary will be their standard-bearer in the fall.

Former House speaker Newt Gingrich, who had been in the running to become Trump’s pick for running mate, tried to do damage control in his speech. “Ted Cruz said, ‘You can vote your conscience for anyone who will uphold the Constitution,’ ” Gingrich said. “In this election, there is only one candidate who will uphold the Constitution.”

Rep. Joe Wilson (R-S.C.), who endorsed Sen. Marco Rubio (R-Fla.) in the primary, said Gingrich did a good job putting Cruz’s remarks in context. But he predicted that Cruz’s refusal to endorse Trump would hurt him.

“The first time I ran for state Senate, the incumbent I defeated, who had signed an oath to abide by the primary results, then went against me in the general election,” Wilson said. “So that’s always been important to me: If someone signs an oath, they should abide by it.”

New Jersey Gov. Chris Christie, a Trump supporter who ran against Cruz, blasted the Texan’s speech as “awful” and “selfish.”

Roe went after Christie on a Philadelphia radio station.

“That guy turned over his political testicles long ago,” Roe said on the Chris Stigall show. “So I don’t take what he has to say with any meaning.”

Katie Packer, a Republican strategist who founded Our Principles PAC in a vain attempt to stop the Trump nomination, called the Cruz speech a “Rorschach test.”

“If you can’t stand Trump, like me, you saw it as bold,” she said. “If you love Trump, you saw it as a betrayal. If you don’t like Trump but have been cowed or fallen in line, you saw it as self-serving because you need that to feel better about your own weakness.”

She said that she believes that Cruz will “be a force to be reckoned with” in the next presidential election but that he will have to account for “creating a mess” as the party should be uniting.

“At the end of the day the GOP is going to need to grow beyond its base to win nationally in a general election,”she said. “Cruz is not the candidate who will help accomplish that.”

The call for unity was the sentiment of many on the convention floor.

“There’s a lot of diversity in our party, and that’s a strength of our Republican Party,” said West Virginia Attorney General Patrick Morrisey. “I have a lot of respect for Ted Cruz. But I’ve made the choice that I’m all in to defeat Hillary Clinton, and everyone should be all in to defeat Hillary Clinton.”

Clinton has been a stronger unifier of the Republican Party than Trump. As happened during the first two days of the convention, the hall broke into calls of “Lock her up!” on Wednesday when those onstage referred to the controversy over Clinton’s unauthorized use of a private email server when she was secretary of state.

Cruz had told Trump on Monday that he was not going to endorse him, chief Cruz strategist Jason Johnson said.

However, the senator did not share the text of his speech in advance of its delivery with the Trump campaign or Republican officials, according to a senior convention official familiar with the program. Text of the address was delivered to party officials shortly before its delivery.

The official, who spoke on the condition of anonymity because he was not authorized to discuss convention planning publicly, described Cruz’s decision to withhold an endorsement as a “cheap shot,” especially after Republican National Committee Chairman Reince Priebus allowed a prolonged roll call of the states Tuesday night to formalize Trump’s nomination and publicly record the raw delegate totals.

“He could have said, ‘I encourage you to vote for Republicans up and down the ballot.’ . . . This was not a Ronald Reagan moment,” the official said.

Trump tweeted a response, referring to the promise by all primary candidates to support the eventual nominee: “Wow, Ted Cruz got booed off the stage, didn’t honor the pledge! I saw his speech two hours early but let him speak anyway. No big deal!”

Cuccinelli, a Cruz adviser who had led the procedural revolt against Trump’s nomination, said he escorted Cruz’s wife, Heidi, from the arena after her husband’s speech because he was concerned for her safety. He said she had only one RNC staffer with her and no security personnel.

“I pulled her away so she could get out. People were closing in on her physically,” he said. “People in my own delegation started approaching her and yelling at her. Someone pointed at her and said, ‘Goldman Sachs.’ ”

He said he was surprised by the reaction.

“I thought everybody would just let Cruz have his 15 minutes,” Cuccinelli said. “It was intended as a courtesy, but they were just wired so tight to react so negatively to Ted.”

Dave Weigel, Louisa Loveluck, Wesley Lowery, Ed O’Keefe, Philip Rucker and Isaac Stanley-Becker contributed to this report.

Correction: An earlier version of this article misidentified Texas delegate Thomas Mathis as Shawn McAwney.