CLEVELAND >> Amid the balloons and parties, speeches and spectacle, one faction of the Republican Party will be almost invisible at the national convention this week: the Bush family network.

Representatives of the last Republican White House are effectively in exile from presidential politics these days, dispirited by their party’s embrace of Donald Trump, the presumptive nominee, and feeling betrayed by former friends who are backing him.

When Trump is nominated, former President George W. Bush will be on his Crawford, Texas, ranch, painting and bike riding. His former secretary of state, Condoleezza Rice, will be in her Stanford University office working on a new book about democracy, and former Gov. Jeb Bush of Florida will, he wrote in a terse email, be “working in Miami.”

They are hardly the only ones staying away. An email sent to alumni of George W. Bush’s administration this month listing those former Bush officials going to Cleveland was notable mostly because of who was not included: no former Cabinet officials or members of the White House senior staff.

The former president, who turned 70 this month, has taken a vow of silence about Trump in public. But he and his longtime loyalists are confounded about what has happened in their party, and by how little appeal the Bush brand of politics carries these days.

“I’m very fearful for my republic,” said Marc Racicot, the former Montana governor who was chairman of Bush’s re-election campaign and of the Republican National Committee. “I thought my fellow citizens would exercise the judgment to steer the country in the right direction.”

Carlos Gutierrez, who served as commerce secretary to Bush, said “People are puzzled by what happened, wondering how did we let this happen.”

Addressing a few hundred Republican donors clad in blazers and polo shirts at a fundraiser for Sen. Roy Blunt of Missouri outside St. Louis last month, Bush did not mention Trump by name but issued an unmistakable warning about the dangers of Trump’s politics.

“He said he was concerned about three isms: protectionism, isolationism and nativism,” recalled John C. Danforth, a former senator and U.N. ambassador for Bush who attended the $1,000-a-person dinner. “I think that said a lot.”

The departure represented by Trump is dramatic.

The presumptive nominee, who has electrified audiences with jeremiads against Hispanics and Muslims, has disregarded the former president’s effort to create a durable Republican majority by broadening the party’s appeal to accommodate a rapidly changing country. He has even more thoroughly rejected Bush’s worldview, scorning the interventionist and pro-free trade and immigration policies that were at the heart of his two terms as president.

And with his penchant for cutting ridicule and crude insults, Trump represents personal qualities that are the antithesis of Bush’s mix of Christianity and old-money restraint.

“It would be like if George Wallace had succeeded John F. Kennedy and the New Frontiersmen,” said Peter Wehner, a senior official in Bush’s White House.

But as Jeb Bush and Sen. Marco Rubio of Florida learned in their failed campaigns, there was little appetite in the Republican primary electorate for a restoration of “compassionate conservatism” or anything resembling the former president’s agenda. Voters wanted a more hard-line approach.

“Our party is changing,” said Matt Schlapp, who was White House political director in George W. Bush’s first term, pointing to rising concern over what he called American “sovereignty.”

“People feel like they’ve lost the country,” Schlapp said of today’s Republican voters.

And many in Bush’s circle feel as though they have lost their party, at least for now.

Bush addressed the 2008 convention by video (Hurricane Gustav was bearing down on the Gulf Coast) and was featured alongside his father in a brief video during the 2012 convention. But if neither John McCain nor Mitt Romney, the last two Republican nominees, was eager to highlight the unpopular Bush, there were still ample reminders of him at their conventions.

Rice, who worked in both Bush administrations, gave one of the best-received prime-time speeches in 2012. And plenty of Bush’s loyalists were at both conventions, either as advisers to McCain or Romney, or because they always attended the party convention, which served as an informal reunion for old friends and colleagues.

This time, though, there will be no high-profile Bush veteran addressing the delegates. The most prominent figure here from the administration will probably be Karl Rove, who is attending both party conventions this year in his role as a Fox News commentator.

While many in the Bush circle are discouraged about Trump, they are also enjoying a bit of schadenfreude over the candidate’s struggles.

Over breakfast with a handful of leading Republicans last month in New York, Jeb Bush made clear he was still smarting over seeing his own presidential ambitions extinguished by Trump. “He seems low energy with the teleprompter,” Bush said, gleefully repurposing Trump’s favorite criticism of him, according to an attendee who requested anonymity to discuss a private event.

Trump tormented not just Jeb Bush in the primary; he also assailed George W. Bush in remarkably pointed terms, arguing that the Iraq War was built on lies and that the former president had little national security record to stand on because the Sept. 11, 2001, attacks took place on his watch. But the contempt Bush loyalists have for Trump is driven by something deeper than his primary-season attacks.

Unlike the last two presidential races, in which the Republican nominees were largely aligned with Bush’s free-market worldview, this campaign may have profound implications for the Bush legacy. Trump’s success — or defeat — in the election would render a verdict on Bush’s presidency and vision of conservatism.

“If Donald Trump wins, he will, by definition, have created a new template of success for Republicans,” said Ari Fleischer, Bush’s first White House press secretary. “But if he loses, and particularly if he is crushed, it will reset the party back more in the direction of President Bush.”

Because Trump represents something far greater in the eyes of the Bush veterans than just an unfortunate party nominee, their determination to defeat him has become more intense.

The vast majority of the approximately three dozen veterans of Bush’s administration contacted for this article indicated that they would not cast a ballot for Trump.

“I can count on one hand the number of people I worked with who are supporting Trump,” said R. Nicholas Burns, a former Bush State Department official who has been calling his onetime colleagues to solicit support for the presumptive Democratic nominee, Hillary Clinton.

A handful of high-level former Bush officials will support him. Most prominent is former Vice President Dick Cheney, who has indicated to former colleagues that with his daughter on the Wyoming ballot for Congress this year, he had little choice. That is an understandable rationale to many in the Bush orbit.

But there is far less charity offered to two other former Bush staff members who have been outspoken on television and social media about their support for Trump: Fleischer and Schlapp.

After Fleischer announced his support on Twitter for Trump in May, one of his former colleagues, Tony Fratto, responded: “Then we don’t have anything to say to each other.”

In an interview, Fratto, who served in the Bush Treasury Department and White House, was still angry. “You were the White House spokesperson when Trump said the president lied the country into the death and maiming of people unnecessarily,” he said of Fleischer. “How can Ari be OK with that?”

Such a betrayal, Fratto said, was “unforgivable.”

Fleischer said he still considered Fratto a friend, but lamented that “Trump has split the party.”