When he suffered a stroke, Frank Luntz blamed it on the anger and tension coursing through him after decades of inhaling America’s toxic political culture. The country’s best-known pollster found himself hospitalised for nearly a week with dangerously high blood pressure.

Two years later, Luntz regards the experience as a turning point. “That completely changed my outlook,” he says. “The loudness of my voice has changed. The speed in which I speak is changed. I’m slower and I’m quieter and I think about what I say. It’s not that I’m trying to be careful, it’s that I really analyse stuff that comes out.”

The 59-year-old, well known from countless media appearances and for running focus groups that provide an insight into America’s political psyche, has also now chosen a less partisan path. Having once worked for rightwing Republicans such as Pat Buchanan, Newt Gingrich and Rudy Giuliani, he no longer hesitates to condemn Donald Trump’s pernicious influence or fears the conservative media backlash.

“If I didn’t die, I’m not afraid any more, so you will hear me criticise people I never would have criticised two years ago. What are they going to do to me? It can’t be any worse than what I’ve been through and, when you become more fearless, it makes life easier to navigate.”

Often seen on TV as ebullient and garrulous, Luntz has felt tired all the time following the stroke. He is visibly so as he holds court with half a dozen British newspaper journalists in his downtown Washington luxury condo, a kitsch affair with faux classical columns, built-in saloon bar (“Frank’s sports bar”) and busts of presidents George Washington (wearing a mask) and Abraham Lincoln.

Luntz’s motivation for this unusual gathering, it seems, is to express gratitude to Britain. He is one of those old school American conservatives who says, “I believe in the special relationship very much,” and is tickled by how the nations rhyme and how they don’t. Last year he went to the UK for a month and ended up staying nearly eight, finding an antidote to American’s poison.

“I was in real trouble when I got to Britain, in real emotional trouble,” he admits. “I still haven’t fully recovered from my stroke, and what goes on in this country, I couldn’t talk about it. I got in the middle of it. Tucker Carlson [a host on Fox News] was killing me every fucking night.”

Luntz, who studied British voters for a conservative thinktank, the Centre for Policy Studies, also invited UK journalists to disseminate a warning: don’t let British politics become as polarised and debased as the American system.

“You still like each other, you still respect each other, you still value public debate: your democracy is still functioning,” he insists. “Ours has seized up and I don’t know how to get ours flowing again. Be thankful that you don’t have our poison … I’m very afraid of the American system being hopelessly damaged.”

Doesn’t the acrimony of the post-Brexit era suggest that the UK is already heading in that direction? Not so, Luntz insists. “You all have proven that there’s still a desire for substance in politics, not just slogans and soundbites, and thank God you haven’t completely embraced American politics because your elections are of substance rather than style.

“I know that you guys are critical of the UK in recent times for being too American in your elections. You’re not. We are becoming more and more superficial. You are still substantial.”

Later he plays a video clip of one of his US focus groups descending into angry shouting and recriminations, a glimpse of a society that seems to be falling apart. He comments: “The worst of the worst. This is my warning to you. This is shit. This is a disaster and it will come to you if you let it happen.”

During his time in Britain, Luntz met several prime ministers in quick succession: John Major (“he’s the most sensible person in the UK”), Tony Blair (“brilliant – he gets it more than anyone”), David Cameron (“still the best communicator that I’ve ever worked with”) and Boris Johnson (“the most fun: when I saw him, he spent 10 minutes just ripping me before I even got to the stuff I wanted to show him because we knew each other at Oxford”), who had not yet become embroiled in “partygate”.

Ever the anglophile, Luntz does not share a view expressed by Joe Biden in 2019 that Johnson is a “physical and emotional clone” of Trump. “Boris Johnson has written more books than Donald Trump has read. Boris is the real Trump. He understands the hopes and dreams of the public. He gets the historic context. He can wax poetically about 2,000 years ago, 200 years ago and two years ago. Trump could not do that.

“Trump captured the anger and the desire for revenge; that is not Boris at all. Think about it: Boris is amusing whereas Trump was vitriolic and mean; Boris is compelling whereas Trump was insulting. There’s a big difference. Boris is more likable, more approachable, more human than Trump was. Trump is more the middle finger; Boris was the kind of guy that you wanted to hang out with at the pub.”

Last week Luntz was hired by the New York Times to take the temperature of 14 independent voters after Biden’s first year in the White House. They weren’t happy. “Biden does not understand the hopes and dreams of the average American,” says the messaging expert, who remains on the centre-right. “He does not empathise with them. His team is ideological rather than emotional and so he’s missing all this. It’s how people feel even more than how they think; feeling is a deeper emotion and Biden is not connecting to them at all.

“Inflation is ‘transitory’? The line that I would use would be we should transitory Joe Biden right out of office, and the public would do that. Secondly, you got Kamala Harris, who comes across as inauthentic with that laugh. He picked her up and put her there, so they’re regarded as a team, and as a team they’re failing.”

Biden’s approval rating is hovering in the dismal low 40s as the coronavirus pandemic drags on interminably. Luntz argues that he overpromised. “He created unrealistic expectations. He’s a very arrogant human being and very flawed and the combination of flaws and arrogance is a really unhealthy cocktail.”

Wasn’t Biden supposed to be Mr Empathy? “There’s nothing about him that screams empathy. There’s everything about him that screams someone who’s already made up their mind.”

A referendum on Biden looms in the midterm elections in November. Luntz agrees with the conventional wisdom that Republicans will win the House of Representatives but thinks Democrats will cling on to the Senate. He identifies six issues that will determine voters’ choices: crime, immigration, shortages, prices, education and the January 6 insurrection. “Democrats have a huge problem on five out of the six.”

Prices, the cost of living, are the biggest problem. “This is the issue that’s going to kill the Democrats because it affects every single voter in every possible way every day of the year, whether it’s food or fuel, whether they’re trying to buy a house or car or something small. They know that it’s impacting them and it’s going to continue for a little while longer. Every day that it continues, you can assume that another member of Congress loses their job. It’s that big a deal.”

An Atlantic magazine interview with Luntz in 2014, a year before Trump began his run for president, was prophetic about his health as a metaphor for America. He complained about a six-day headache and sleeping two or three hours at a time. Voters were “contentious and argumentative” and “didn’t listen to each other as they once had”. The article’s author, Molly Ball, wrote: “Frank Luntz is having some kind of crisis. I just can’t quite get my head around it.”

Today, after the catharsis of his stroke, Luntz finds plenty of blame to go around. He casts a harsh light on the media, social media and his own younger self. In an infamous 2003 memo, for example, he advised George W Bush’s Republican party to abandon the phrase “global warming” in favour of “climate change” because it is “less frightening”. He is now an advocate of climate legislation. “I’ll take my blame for the stuff that I did 20 years ago. But I figured it out.”

He touches a button and a giant painting of man walking on the moon slides up to reveal a TV screen and slideshow presentation of polling data entitled The Great Rethink. It is a study of America voters’ attitudes and disillusionment with their leaders. “The only thing we agree on is that politicians suck,” Luntz says. “If you’re American, this is a very depressing time right now.”

One slide is about what people want most in life: fewer hassles, more money, no worries, better work, more choices, more time, better lifestyle, better work-life balance. Another offers some words to use (I am your voice, accountability, fact-based) and words to lose (agenda, I’m listening, transparency).

Luntz argues that even in a polarised society such as America, every parent asks the same question: will my child/grandchild be happy? Perhaps rather optimistically, he urges politicians to focus on children as “the great unifier”.

“If you want to bring people together, you do it over their children. You guys are divided on just about everything; this crushes that divide. This brings people together and it’s not been done before. I’m waiting for a political party or movement to capture the next generation as their focus.”

Luntz, who does not think he will be in the polling business much longer, hopes politicians will consider the lessons of his “Great Rethink” presentation and rethink their own ways before democracy seizes up for good. “I want to hit them over the head with this,” he says. “I want to be able to say to them: cut it out. Just stop. Nothing is worth destroying the country – and you are this close to destroying the country.”