Donald Trump spent much of a big rally thrashing Republican rivals who no longer threaten him

Donald Trump may be trying to unite the Republican Party, but he's still having fun mocking his former rivals.

During a Wednesday rally in Southern California, the presumptive Republican presidential nominee ran through some of his most high-profile rhetorical attacks on Republican Party figures.

For one, Trump laid into 2012 Republican presidential nominee Mitt Romney, who last month refused to endorse Trump and called for the real-estate magnate to release his tax returns.

Claiming he had "a store that's worth more money" than Romney, Trump said if Romney would've decided to run for president, "he would've been out quickly."

"I understand losers," Trump said of Romney, who he added "walked like a penguin around the stage."

He continued: "He choked like a dog. You ever see in athletics? He's a choker. And you know the truth, I hate to say it: Once a choker, always a choker. I was nasty about it."

Trump also knocked former Florida Gov. Jeb Bush, who he noted also hadn't endorsed him.

"Jeb hasn't done it yet. He will get a burst of energy, and then he will do it," Trump said, a reference to his favorite campaign-trail insult of Bush. "He needs to get up the energy. No, Jeb has not been nice."

While Trump praised some prominent Republicans like former Texas Gov. Rick Perry and Sen. Lindsey Graham for taking a less adversarial tone, the former reality-television star also referenced his past attacks on both candidates.

Trump told supporters that Perry was a "good guy, good governor." But Trump quickly noted that noted that he "didn't know that he said that during the campaign."

He also said he was surprised, meanwhile, that Graham had called him recently, months after Trump gave out Graham's personal cell-phone number during a campaign rally.

"It was very nice that Lindsey Graham called. Don't forget: I wasn't an angel," Trump said. "I did it on live television, I held his number up, and I think it blew up or something."

Trump did reserve some time for attacks on Democratic frontrunner Hillary Clinton. He called the release of a State Department audit faulting Clinton's email practices "not so good."

Though Trump has made it clear that he's not interested in criticizing his rivals after they drop out, he occasionally can't seem to help himself.

At a rally in February after former Florida Gov. Jeb Bush dropped out of the presidential race, Trump mocked Bush's campaign, sarcastically calling Bush's attempt "brilliant."

"Jeb was going to win. Jeb is gone. He forgot about three words, according to, I'll say it, The New York Times: Donald John Trump," he said.