Donald Trump Jr. Don John Trump'Tiger King' star Joe Exotic requests pardon from Trump: 'Be my hero please' Zaid Jilani discusses Trump's move to cancel racial sensitivity training at federal agencies Trump International Hotel in Vancouver closes permanently MORE has dropped out of a fundraiser for Texas Land Commissioner George P. Bush scheduled for later this month, The Hill confirmed, following Jeb Bush's repeated criticism of President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE.

The decision came after Bush's father, the former GOP presidential candidate, harshly criticized the Trump administration for its "heartless" border policies in a tweet.

But that tweet was far from the first time that Trump's former GOP primary rival took aim at the president, with each criticism chipping away at the efforts between the two sons to build a relationship.

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"Don was originally happy to do a favor for George P. and headline the fundraiser, but after Jeb's incessant attacks, Don decided enough was enough and pulled the plug," a source close to Trump Jr. told The Hill.

Axios first reported the decision to nix the fundraiser, which was supposed to take place in New York on June 25.

George P. Bush is running for reelection in 2018, but is expected to cruise to victory after surviving a tougher-than-expected primary challenge.

Earlier this year, Jeb Bush drew Trump Jr.'s ire when it was reported that he chided the president during a speech at Yale University by saying he goes home to children "who actually love me."

Jeb Bush's team argued that the quote had been taken out of context and was not referring to Trump. But the president's children blasted Bush in the aftermath of the comment.

A source familiar with the discussions between Trump Jr. and George P. Bush told The Hill that the two men spoke earlier this month after Jeb Bush said that the president attacks his rivals to make himself "look strong." Trump Jr. said then that he wouldn't be able to continue helping George P. Bush if the attacks continued.

Trump Jr. has become one of the Trump administration's most sought after surrogates on the stump. He's a regular fixture on Fox News and has been hitting the campaign trail ahead of the 2018 midterm elections.