The upcoming midterm elections for US Congress, the first nationwide vote since Trump supporters stormed the US Capitol nearly two years ago, have many Americans on edge. The BBC's Katty Kay has been finding out why. Karen and Steve don't want to take up arms. But if Republicans lose in November this elderly Arizona couple say a civil war is coming and, yes, they will fight. They have discussed it between them, and feel that taking up arms is their best option. It was at this point that our conversation grew a little dark and my faith in the strength of American democracy grew a little shaky. I met the Slatons at their Trump paraphernalia store in Show Low, Arizona. It was one of the first stops on a month-long road trip that I took around America this summer, a journey to understand why the upcoming elections feel so consequential, perhaps even a little ominous. The couple were delightful hosts. They were funny and generous. They took me on a tour of their extensive stock of whacky Trump merchandise and explained that, yes, there really are people who want a $100 life-size cut-out of the former president dressed as Rambo to put in their living rooms. Quite a lot of people actually. Trump as Rambo is one of their best selling items. We talked about history, the economy and even abortion. But it was only when I questioned their belief that the 2020 election was stolen that things got tense. Wasn't it possible, I asked, that millions of Americans just didn't like President Trump and so Joe Biden won the election? It was Karen who responded, with a distinctly steely glint: "If you're a crazy liberal, we're just not interested. The central news, let me call them, I'm not going to call them fake news, but it is fake news to say that America doesn't like Trump. America loves Trump." "It will start on a small scale, it will be like town against a town, state against a state," Steve had clearly thought this through. People have been tossing this idea of a second American civil war around for a couple of years now, ever since the 2020 election, ever since the violence of the Capitol Riots on 6 January, 2021. I find it hard to believe - maybe I lack imagination - but the idea of Americans going to war over a lost election still seems implausible. But that's Steve's take on what happened last time: "When Lincoln won, that triggered the South." That's not the only view of the origins of the American Civil War, but this wasn't the moment for a history debate; it's the present that needs attention. As I said goodbye to the Slatons, Steve threw out a warning. It was said with a habitual American friendly smile, but it was chilling nonetheless: "This could turn really nasty." Just how nasty was what I was trying to find out. Americans cast their ballots for control of Congress every two years. The congressional elections that fall in years when they aren't voting for president are called midterms. Because the White House isn't up for grabs, midterms generally don't get much attention and turnout hovers around 40%, lower than the 50-60% that vote in presidential elections. But this year feels different. This is the first national election since the storming of the Capitol and will test whether America can hold an election without violence. And, to be clear, the war talk from Americans like the Slatons is not normal pre-election rhetoric. In two and a half decades in America I've covered 10 US election cycles, I have never heard voters talk about politics in this violent way. Karen and Steve's views are not fringe views either. The belief that the 2020 election was stolen has seeped into the mainstream like a virus that now infects the entire democratic process. Polls since the election suggest that about 70% of Republicans believe Joe Biden is not the legitimate president. That's about one third of the American electorate, or more than 50 million people - not far off the population of Britain. This summer on a tour of Arizona, Wyoming, Georgia and Pennsylvania, I spoke to dozens of voters who are convinced Joe Biden is not America's legitimate president. If you felt an election had been stolen from you, you'd be angry too. Indeed, maybe you'd feel it was something worth fighting for. The problem is there is no evidence to support the stolen election claim. More than 60 lawsuits were brought by Trump's lawyers claiming election fraud. All but one was dismissed for lack of evidence. Some of the suits were even heard by Trump appointed judges, and they, too, tossed the cases out. Key Republican election officials in battleground states, like Arizona, and Georgia, also said the election process had been fair and accurate. There is no evidence of fraud that would have overturned Joe Biden's win.