Donald Trump Donald John TrumpBiden leads Trump by 36 points nationally among Latinos: poll Trump dismisses climate change role in fires, says Newsom needs to manage forest better Jimmy Kimmel hits Trump for rallies while hosting Emmy Awards MORE tore into primary rival Ted Cruz Rafael (Ted) Edward CruzMurkowski: Supreme Court nominee should not be taken up before election Battle lines drawn on precedent in Supreme Court fight Sunday shows - Ruth Bader Ginsburg's death dominates MORE on Friday morning, saying he would not accept the Texas senator’s endorsement and threatening to fund a Senate challenger against Cruz.

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"If he gives it, I will not accept it," Trump, the GOP presidential nominee, said at a Friday morning press conference in Cleveland.

“He’ll come and endorse in the next little while because he has no choice,” Trump added. “I don’t want his endorsement. Ted, stay home, relax, enjoy yourself.

"Honestly, he should have done it, because nobody cares, and he would have been in better shape four years from now — I don't see him winning anyway frankly, but if he did it's fine. Although maybe I'll set up a Super PAC if he decides to run," he added.

Cruz, a GOP senator from Texas who finished second to Trump in the GOP primary, defended his non-endorsement of Trump on Thursday, stating that his speech was intended to provide a clear unified vision for the Republican party.

"Discussing what we should stand for — that we should be standing for freedom and defending the Constitution — is a message of unity. And as I said last night very explicitly, the way to unify the party is not to scream and yell and hurl insults," he said. Cruz has also said he would not endorse Trump given his insults of Cruz's wife and father. The GOP senator's Wednesday night convention speech drew the ire of many Republicans who are now calling on him to get behind Trump and unite the party ahead of November.

Trump said Cruz's speech might have hurt his future political ambitions.

“Somebody got booed out of the place by thousands and thousands of people,” Trump said. “Honestly, he may have ruined his political career.”

Nikita Vladimirov contributed.

- Updated at 11:14 a.m.