Thanking his volunteers in Cleveland a day after the Republican National Convention wrapped, GOP presidential nominee Donald Trump today slammed Ted Cruz's Wednesday night speech and said he “will not accept” if the Texas senator ever decides to endorse him.

"Honestly, he may have ruined his political career. I feel so badly," Trump said this morning of Cruz, his former primary rival.

Cruz was booed off the stage on the third day of the convention for suggesting that people should “vote their conscience” in November. The Texas senator defended his speech the next morning at a Texas delegate breakfast, arguing he’s “not in the habit of supporting someone who attacks my wife and attacks my father.”

But Trump said this morning that Cruz will “come and endorse over the next little while. It's because he has no choice. But I don't want his endorsement. What difference does it make?"

"Ted, just stay home, relax, enjoy yourself," Trump said to laughter from the crowd of supporters and convention volunteers.

Trump said he reviewed a version of Cruz's speech, which included no endorsement, but allowed him to take the stage anyway Wednesday night.

“He got up and he added a sentence, which could have been viewed as a nasty thing in terms of what he said because he was implying something which is wrong. But that's OK,” Trump said, referring to Cruz’s “vote your conscience" line.

Trump also called Cruz “dishonorable” for not supporting him and thereby rejecting the pledge each GOP candidate signed during the primaries indicating they would support the eventual party nominee.

"I like Ted, he's fine. Again, don't want his endorsement," Trump said. "If he gives it, I will not accept it, just so you understand."

Although they started the primaries cordially, Trump and Cruz were engaged in some heavy mudslinging at the end. Cruz called Trump a “pathological liar” and “utterly amoral.”

Trump got into the habit of calling Cruz “Lyin’ Ted” and insinuated that Cruz’s father, Rafael, was a conspirator in President John Kennedy’s assassination. Trump even went as far as to share a tweet with an unflattering photo of Cruz’s wife, Heidi, alongside a photo of his ex-model wife Melania.

Trump defended himself today in circulating the tabloid story about Cruz’s father.

“All I did is point out the fact that on the cover of the National Enquirer there was a picture of [Rafael Cruz] and crazy Lee Harvey Oswald having breakfast,” Trump said of the unsubstantiated allegations, adding that Cruz’s father is a “lovely guy.”

On Heidi, Trump insisted, "I didn't do anything."

“I think Heidi Cruz is a great person. I think it's the best thing he's got going, and his kids, if you want to know the truth,” Trump said.

Today, alongside running mate Mike Pence, Trump spent equally as much time celebrating the four-day convention as he did attacking his former opponents.

“It was amazing. There was great love in that room,” Trump said.

He also thanked his team, called RNC Chairman Reince Priebus a "superstar," and congratulated his family on their speeches.

Trump also took the time to give himself a pat on the back for his speech on the final night of the convention. Trump said he didn't mean to make his speech long, but "what happened is the applause was so long and so crazy."

Trump also argued the TV ratings for the convention "were through the roof."

"We created one of the most successful conventions in the history of conventions," Trump boasted.

But Trump's message today was one directed at those who still are not aboard the "Trump train."

“No matter how much you like, or dislike, no matter what your feelings, whether you're the governor of Ohio, whether you're a senator from Texas,” Trump said, referring to Ohio Gov. John Kasich, who also hasn't endorsed Trump and skipped the convention.

“Or any of the other people that I beat so easily and so badly, you have no choice, you got to go for Trump.”