Relaxing in the drawing room of Chevening in a red-and-pink chair, JD Vance kicked off his summer break with a mini press conference. Flanked by David Lammy, the vice-president waxed lyrical on everything from Israel to fishing. But he had less to say when a reporter asked if he was the frontrunner for the Republican nomination in 2028. “I don’t want to talk about lowly things like politics in this grand house. Come on,” he replied, keen to change the subject.

Yet there’s no denying that Washington is bubbling with speculation about the succession in three years’ time. President Trump set the hare running on Tuesday when he was asked by a Fox reporter whether he would “clear the field” and confirm that Vance was his heir apparent. Trump didn’t go all in but he did concede his deputy was the “most likely” and “would be probably favourite at this point”. He then brought up his secretary of state, Marco Rubio, as “somebody that maybe would get together with JD” on a Republican ticket.

“These things start way sooner than they should,” said Henry Barbour, a political strategist who spent 19 years on the Republican National Committee. “The reality is the race for 2028 started when President Trump decided who was going to be his vice-presidential nominee.” Back then, Vance beat Rubio to the role after Trump concluded he lacked chemistry with the Florida senator (he had also considered Robert F Kennedy Jr but decided he was “too crazy”).

On a podcast last week Katie Miller, the wife of the influential Trump aide Stephen Miller, put to Vance the idea of a joint ticket. In response, he spoke warmly of Rubio, referencing his sweet tooth (“half the time that I see Marco in the hallway it’s because he’s been down to the Navy mess in the White House and he’s gotten a bunch of ice cream”) and sense of humour — recalling a joke he cracked about a woman in his district trying to get her dead husband’s body back from Israel. “She said ‘maybe I don’t want him back, the last time somebody died over here they rose from the dead three days later’. I didn’t know until the very end that it was a totally bullshit joke.”

Pope Leo XIV meeting with U.S. Vice President JD Vance and Secretary of State Marco Rubio at the Vatican.

Rubio, left, and Vance met the new Pope in May

SIMONE RISOLUTI/VATICAN MEDIA

The biggest question for Republicans is who can keep together the winning coalition that Trump assembled at the 2024 election, adding peaceniks, black and Latino men, granola moms and vaccine sceptics to the party’s traditional core of older white conservatives.

While Democrats are quick to snipe (“Vance has no charisma. He’s not Trump,” said one), a Vance-Rubio ticket would have some advantages. Neither man was born rich and both have compelling back stories. Vance is a rust belt intellectual who loves a fight and has deep ties to the libertarian tech billionaire Peter Thiel. Rubio is a smooth-talker from wealthy Miami who, as the child of Cuban immigrants, also represents the new Republican voter. Hispanics had the biggest swing to Trump in 2024. “Vance can speak to the working class. Rubio can reassure the country clubs and Latinos,” one Republican said. Both are also young by presidential standards: Vance is a spring chicken at 41 and Rubio is 54. “They could wait two more cycles and still be very much candidates,” one insider said.

Of the two, Vance has been the more consistently isolationist — though the longstanding critic of US funding for the Ukraine war spent Saturday at Chevening meeting national security advisers from Europe, the US and UK before Trump’s summit with Putin on Friday.

Would they miss out by not having a woman as part of the team? “Don’t be woke,” a Maga figure urged. “No one cares.”

Yet there are obvious concerns too.

Would Rubio really be happy to play second fiddle after running for the presidential nomination in 2016? “To envision yourself as the leader of the free world and then to say, ‘Oh yeah, no I’m not really interested any more, that’s not really a goal,’ would be untrue for Marco Rubio in the same way it would be untrue for so many others who have stepped on those debate stages,” said Manuel Roig-Franzia, author of The Rise of Marco Rubio. “People have told him since he was a young man that he could be president one day and I think he’s believed it since he was a young man.”

Second, voters rarely choose to promote vice-presidents to the top job. Of the 50 US vice-presidents since 1789, only 15 have gone on to become president, of whom eight took the role after the death of a president.

David Lammy and JD Vance fishing at Chevening House.

Vance with Britain’s foreign secretary, David Lammy, at Chevening. Serving as vice-president may not give him an edge, if history is anything to go by

SUZANNE PLUNKETT/POOL/AP

Vance has courted the limelight more than most vice-presidents, which brings its own risk. “There’s always a chance Trump finds it too much,” one insider said. On the 2024 campaign trail he was accused of lacking warmth and in DC it’s not gone unnoticed that he has embarked on a slew of podcast appearances showing his softer side.

Meanwhile Rubio, who in 2016 called Trump “an embarrassment”, has become one of the president’s most trusted team members, regarded as an adult in the room who is also at home with true Maga believers.

Old-school Republicans look on with a sense of horror wondering if their guy has lost his principles. The politician who once quoted Reagan and championed soft power and overseas intervention now dismantles USAid and takes an America First approach. Social media users post “Free Marco” when he appears at cabinet. “Marco Rubio is not ideological but he is opportunistic as far as how he’s evolved,” said Roig-Franza, the biographer. “You are seeing the maturing of Marco Rubio happening before our very eyes.”

Rubio and Vance both face questions over their authenticity. “Rubio is such a neocon,” said a senior Maga figure. “The movement kind of still hates him. As for Vance, he’s just not in the fight.” Some in Maga agree with Vance’s isolationism but see him as too close to Silicon Valley. Another is more diplomatic: “It’s been six months. Vance still needs to prove himself.”

Other Republicans thought to be considering a tilt in 2028 include Glenn Youngkin, the more moderate governor of Virginia, and Sarah Huckabee Sanders, the governor of Arkansas who was previously Trump’s White House press secretary. Expect the list to grow. In Maga circles, some predict a field of 30 candidates when the time comes. “Do not write off Eric Trump,” said one Washington old timer. “My view is this will be wide open,” Barbour added.

Donald Trump and Eric Trump at a golf course ribbon-cutting ceremony.

President Trump with his son Eric, 41, at a golf course opening near Aberdeen last month

JACQUELYN MARTIN/AP

But there’s an alternative scenario. Will there be a vacancy to fill? Trump has flirted with running again, although the constitution prohibits it. Lately he has suggested he will indeed step down after his second term but others hope to change his mind, arguing he is essential to the Republicans staying in power. Legal routes are being explored.

As Steve Bannon, the former White House strategist who has himself been reported to be considering a presidential bid, told me: “President Trump is the only candidate that guarantees victory in 2028 — that’s why people are working feverishly to make this a reality.”