It’s hardly a mystery that former President George W. Bush is backing his brother’s presidential campaign. But in Colorado over the weekend, the former president reportedly told a group of Republican donors which candidate he dislikes on a personal level. Politico reported:

Inside a sleek Denver condominium, George W. Bush let a hundred donors to his brother’s campaign in on a secret. Of all the rival Republican candidates, there is one who gets under the former president’s skin, whom he views as perhaps Jeb Bush’s most serious rival for the party’s nomination.

It isn’t Donald Trump, whose withering insults have sought to make Jeb pay a political price for his brother’s presidency. It isn’t Marco Rubio, Jeb’s former understudy who now poses a serious threat to his establishment support.

“I just don’t like the guy,” Bush said about Ted Cruz, according to “more than half a dozen donors who attended the event” and spoke to Politico.