Donald Trump will move forward as the presumptive Republican nominee without endorsements from the only two living successful Republican presidential candidates. When the Texas Tribune reached out to former Presidents George H.W. Bush and George W. Bush, both said they were not going to participate nor endorse anyone in this presidential campaign.

The current question before the Trump campaign — even before ramping up fundraising to meet the size of Clinton’s war chest (so much for self-funding to avoid the corrupting influence of money raising) — is whether his campaign can unite the Republican Party. And the Bushes’ absence is notable because Bush senior has endorsed the GOP nominee for every presidential campaign since his own, starting with Bob Dole in 1996. Twenty years ago, those two were bitter rivals. But when the general election rolled around, Bush didn’t take his ball and go home. Instead, he said, “I’ll do anything Sen. Dole wants me to do — I’ll campaign for him.”

For months, bad blood between Trump and the Bushes has been festering. Not only did Trump childishly mock “low-energy” Jeb Bush throughout the campaign. In reality-TV fashion, Trump dabbled in “Trutherism” by claiming that George W. Bush “did have advance notice” about the 9/11 attacks. He also denounced Bush’s decision to go to war rewriting history in the process. Maybe Trump’s comments can be forgiven after a tough campaign season. Yet whatever the Bushes are or aren’t, they’re dignified and respectable men, so it’s pretty obvious to us why they’d decline to endorse a boorish loudmouth who basically called Bush 43 a war criminal.

Trump, meanwhile, couldn’t care less. And why should he? When he heard the news, the presumptive GOP nominee said, “I don’t care if they sit it out. I have tremendous support. Even politically so many people are now coming out in support. We’re going to have some people that aren’t going to want to play the game, and it’s okay. If they don’t want to. I don’t think it matters.” In this case, Trump is correct: He won because of grassroots anger at the party’s establishment — anger directed in part at the Bushes.