Bill Kristol, editor-at-large of The Bulwark and director of the advocacy group Defending Democracy Together, once served as chief of staff for Vice President Dan Quayle under President George H.W. Bush. Today, he watches the Republican Party with disbelief, observing a dramatic shift in its values and leadership.

As he scoped the Republican National Convention this week in Milwaukee, where traditionally senior party leaders mingle with younger ones, Kristol was struck by how few of his old colleagues were there.

“Most of the people I knew aren’t there. They either checked out of politics, or they checked out of the Republican Party, or they’re out of office,” Kristol told Boston Public Radio on Thursday.

To Kristol, that exodus is a reflection of the serious transformation that has occurred within the party, now dominated by Trumpism.

“The party has really been transformed. This is not just a 30-degree or a 50-degree alteration. This is not moving a little in this direction or that direction,” he said. “This isn’t just different from [the past] but really repudiates so much of the Bush, McCain, Romney Republican Party.”

He added: “Just look at the members of Congress, look at the members of the Senate, look at the most prominent Republican governors. It’s not like, you know, there are a whole lot of Mitt Romneys and Paul Ryans.”

When asked if Trump is to blame for the party’s current state, Kristol said it may have started because of Trump, but it’s grown a momentum of its own.

He likened Speaker of the House Mike Johnson, Florida Gov. Ron DeSantis and Texas Gov. Greg Abbott as representative of elected officials who diverge from the Republican Party Kristol knew.

“It wasn’t that long ago that Jeb Bush was governor of Florida … George W. Bush was governor of Texas,” he said. “It symbolizes, in a way, how much things have changed.”

Kristol cited JD Vance — who once opposed Trump but is now his running mate — as an example of the shift. arguing that Vance is more extreme ideologically than Trump. For example, he mentioned Vance’s stance on sending zero aid to Ukraine.

Even Mike Johnson, who Kristol describes as “pretty conservative” led half the House Republicans to vote yes to aid for Ukraine. Vance “was just vehemently opposed to that,” Kristol said.

For Kristol, these changes are here to stay, at least for now.

“I think it will take a while to shed Trumpism if the party ever does, or does in the near future,” he stated.