CLEVELAND -- The morning after he torched the convention floor -- and possibly his presidential aspirations for 2020 -- Ted Cruz reached for more kerosene.

Speaking to his own state delegation over breakfast Thursday, the Texas senator defended his prime-time snub of the Republican Party’s presidential nominee, arguing he would not act as a “servile puppy dog” and endorse Donald Trump, even at the urging of his constituency.

The enduring bitter rivalry between Cruz and Trump clouds the final day of a Republican convention that has been marked by controversy, mismanagement, and discord instead of party unity. As Trump prepares to formally accept the GOP nomination here Thursday night, it’s Cruz who is attracting the spotlight.

The Lonestar State lawmaker’s crusade has been viewed by loyalists and some Trump opponents as one of honor and conviction. But for others in the party, even those who lament the reality of Trump as their standard-bearer, Cruz’s behavior and style cement their disdain for him. "Lucifer is back," former House Speaker John Boehner remarked Wednesday night, a former aide noted.

Cruz seems to be betting his political career on Trump failing miserably in November -- and taking the party down with him. But Cruz’s gambit is fraught with risk. The negative reaction from Texans who voted him into the U.S. Senate raises the stakes on his re-election bid in 2018, and his White House hopes for 2020. If Trump and other Republicans falter, he could either be excoriated as the catalyst or praised, albeit by a narrow group, as the faithful defender of conservatism.

The Trump campaign and many in the Republican Party believe Cruz’s political calculation backfired.

“The party is definitely more unified,” Trump Campaign Chairman Paul Manafort told reporters. “There were a number of Cruz delegates on the floor last night who disagreed with what Cruz did.”

The Trump camp had approved the speech, a transcript of which was sent to reporters before the prime-time event. Manafort said Trump allowing Cruz to speak without yet endorsing him showed that he has been “very magnanimous” in his outreach. “There were no conditions put on anything,” Manafort said. But, “everyone who did attend said in his own way that he would support the ticket or endorse the ticket. Only Senator Cruz chose to slip away with something on ‘conscience.’”

Cruz's campaign manager, Jeff Roe, told a Philadelphia radio program that Trump called Cruz earlier this week to wish him luck and ask for an endorsement, but the senator declined. "This is a guy that has a core set of principles and he’s not willing to waver those in the face of intense pressure," Roe said, according to a transcript posted by Buzzfeed.

Rick Perry, who endorsed Cruz during the primary and once called Trump a “cancer on conservatism,” said his fellow Texan’s decision “was a bad call.”

“I don’t want to go back to Texas and explain to people why I was part of the problem and not part of the solution,” the former governor told CNN. “And that a very left-leaning Ginsburg clone is put on the Supreme Court next spring because I couldn’t bring myself to support Donald Trump.”

Perry criticized Cruz for reneging on the pledge he and other Republican presidential candidates made to support the eventual nominee. “If you don’t want to keep your word, don’t be signing pledges,” he said.

Texas delegates shouted down Cruz on Thursday morning for backing away from the pledge and for refusing to endorse Trump and unify the party. “There were some mixed feelings and some hurt feelings in the Texas delegation today,” said Lt. Gov. Dan Patrick, an ardent Cruz supporter who chaired his Texas campaign. “I have been very clear. I support Donald Trump because we must defeat Hillary Clinton in November.”

Despite the criticisms from his own delegates, Cruz remained defiant, arguing he couldn’t uphold the pledge after Trump’s criticisms of his family.

“The day that was abrogated was the day this became personal,” he told the Texas delegation. “I am not in the habit of supporting people who attack my wife and attack my father.”

He continued: “That pledge was not a blanket commitment that if you go and slander and attack Heidi that I’m going to nonetheless come like a servile puppy dog.”

During the primary, Trump threatened to “spill the beans” on Cruz’s wife and floated a conspiracy theory intimating that the senator’s father was tied to the John F. Kennedy assassination

“This is not a social club,” Cruz said. “We either stand for shared principles or we’re not worth anything.”

Cruz said he had made clear he would not come to the convention to support a candidate who bashed his family. He said he would be listening to Trump’s acceptance speech Thursday night. “I am going to be listening to how he and his campaign will conduct themselves every day from now until November."