Presumptive GOP presidential nominee Donald Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE is slamming Jeb Bush for refusing to back him, saying he isn't a "man of honor."

Trump criticized his 2016 primary rival for breaking the pledge he signed last year vowing to support the eventual Republican nominee.

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“Jeb Bush dishonored his pledge. I mean he dishonored his pledge,” Trump said on the "Mike Gallagher Show" on Wednesday, as first reported by BuzzFeed News.

“He signed a pledge, and, if you remember, they all wanted me to sign it, so I signed it. But that pledge is a guarantee, there’s no outs. It doesn’t say, 'subject to me liking Donald Trump' or anything.”

The former Florida governor said last week he doesn't plan to vote for Trump or Democratic front-runner Hillary Clinton Hillary Diane Rodham ClintonWhat Senate Republicans have said about election-year Supreme Court vacancies Bipartisan praise pours in after Ginsburg's death Trump carries on with rally, unaware of Ginsburg's death MORE. Instead, he said he will "support principled conservatives at the state and federal levels."

Trump railed against Bush during the interview for spending $12 million in negative ads against him — most of which he said was "phony."

“And then after he spent it I started hitting him very hard,” Trump said. “And then they said Trump was mean, but I wasn’t mean.

“I had a right to do what I did,” Trump continued.

“And it was tough, and he left, and then he said he’s not gonna endorse me? I said, ‘Well, then you violated your pledge.’ And I think he said, well, he doesn’t care. Well, that’s not a man of honor, when you violate your pledge.”

Other Republican leaders have said they don't plan to vote for Trump in the election.

Sen. Marco Rubio Marco Antonio RubioFlorida senators pushing to keep Daylight Savings Time during pandemic Hillicon Valley: DOJ indicts Chinese, Malaysian hackers accused of targeting over 100 organizations | GOP senators raise concerns over Oracle-TikTok deal | QAnon awareness jumps in new poll Intelligence chief says Congress will get some in-person election security briefings MORE (R-Fla.) has said he will support the Republican nominee and honor his pledge.

Sen. Ted Cruz Rafael (Ted) Edward CruzSenate Republicans face tough decision on replacing Ginsburg Cruz: Trump should nominate a Supreme Court justice next week Renewed focus on Trump's Supreme Court list after Ginsburg's death MORE (R-Texas) earlier this week stalled on endorsing Trump.

Trump said he thinks that "eventually, Ted Cruz will also come along.

"They signed pledges," he said.

"Everybody signed pledges."