Donald Trump and Jeb Bush continue hammering each other after fiery debate

Republican presidential front-runner Donald Trump and one of his rivals, former Florida Gov. Jeb Bush (R), kept swinging at each other hours after their confrontation at Tuesday night's CNN debate made headlines.

Bush talked to CNN on Wednesday and reinforced his point from the debate that Trump is "not a serious candidate."

"I got to post up against Donald Trump," Bush said. "I don't think he's a serious candidate."

He added, "And I don't know why others don't feel compelled to point that out, but I did. And I think I got a chance to express my views and compare them to someone who talks a big game but really hasn't thought it through."

Bush also released an attack ad bashing Trump:

During the debate, Bush went after Trump by calling him a "chaos candidate," attacking his plan for fighting ISIS, and telling him that he couldn't "insult his way to the presidency." Trump didn't take these attacks lying down, however, and fired off his own criticisms of Bush at the debate.

Trump continued his condemnation of Bush at a Wednesday rally in Mesa, Arizona, as he simultaneously dismissed Bush's own broadsides.

"I'm sure nobody watched the debate last night," Trump joked to his supporters. "Nobody in this crowd. This is a very apolitical crowd."

He said CNN ratings for the debate must have been great and joked that maybe he'd sit the next debate out "just to see it tank."

"Last night, I had Jeb come at me," Trump said, turning to his favorite Bush burn: "You know, low energy."

Trump then mocked Bush's attacks on him and said that Bush "said it just the way his pollster told him to say it." He compared his strength to Bush's supposed weakness and got back onto his primary message of making America great again.

"I hit back very, very hard [at Bush], but look, we need strong people, we need sharp people," Trump said. "We are being killed, we are being beaten by everybody, we're not winning anymore. And I finished up by saying, 'We aren't winning anymore.'"

Trump further scoffed at Bush for spending millions on campaign ads despite being so low in the polls.

"Donald Trump, until this point, has spent $211,000. I don't even know why I spent it," Trump said. "And I'm at No. 1 by a lot. ... I spent the least and I have the best result."

Trump then moved on to other topics, but eventually came back to Bush.

"Look what I did to Bush. I haven't even started on Hillary," Trump said. "Poor Bush."

He also mocked Bush for planning negative ads against him.

"I hear now he's doing ... negative commercials on me," Trump said. "He's doing a commercial where he uses what he said last night but he doesn't put what I said to him."

Trump also released a statement on Wednesday responding to the suggestion that Bush wouldn't back him if he won the Republican nomination.

"I really don't want Jeb's endorsement because he is a low energy person and he does not represent strength, power and stamina, which are qualities our country desperately needs," Trump said in the statement. "While everyone said I beat him last night, I was only responding to his desperate attempt to stay relevant by attacking me."