Former President George W. Bush reportedly ripped into Texas Sen. Ted Cruz at a weekend gathering of donors to his brother's presidential campaign, according to a published report Monday. 

Politico reported that Bush said of Cruz, "I just don't like the guy," at the event, which was held Sunday night in Denver.

According to the report, which cited at least six donors who were at the event, Bush said he did not like Cruz's de facto alliance with Republican front-runner Donald Trump, who has notably spared Cruz from the criticism he has ladled onto other members of the 15-candidate Republican field.

"He said he found it 'opportunistic' that Cruz was sucking up to Trump and just expecting all of his support to come to him in the end," one donor told Politico when asked to describe Bush's remarks about Cruz. The report added that the former president had been engaging with amiable discussions about the state of the GOP race when Cruz's name came up.

"I was like, 'Holy s---, did he just say that?'" the donor told Politico. "I remember looking around and seeing that other people were also looking around surprised."

The report also said that Bush warned the donors to not underestimate Cruz's strength in the South and in Texas, where his message of religious liberty is expected to play very well with voters. 

Cruz, in a written statement put out by the campaign on Tuesday, said he would not be "reciprocating" after the comments. 

"I have great respect for George W. Bush, and was proud to work on his 2000 campaign and in his administration," he said in the statement. "It's no surprise that President Bush is supporting his brother and attacking the candidates he believes pose a threat to his campaign. I have no intention of reciprocating. I met my wife Heidi working on his campaign, and so I will always be grateful to him."

Freddy Ford, a spokesman for George W. Bush, did not deny that the former president had made the disparaging remarks about Cruz when asked to comment by Politico.

"The first words out of President Bush's mouth [Sunday] were that Jeb is going to earn the nomination, win the election, and be a great President ... He does not view Senator Cruz as Governor Bush's most serious rival."

Ford denied further requests by Fox News to address Bush's reported "I just don't like the guy" remark.

Cruz joined George W. Bush's presidential campaign in 1999 as a domestic policy adviser and helped put together the legal team that argued Bush v. Gore before the Supreme Court in the aftermath of the controversial election. He later served as an associate deputy attorney general in the Justice Department before becoming Solicitor General of Texas in 2003.

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Fox News' Mike Emanuel and Serafin Gomez contributed to this report.