Donald Trump once famously boasted he could shoot someone on Fifth Avenue, and not lose supporters. For years that seemed true. But his latest actions – including the deployment of an ad hoc paramilitary force against protesters on avenues around the country – may have been too much. New polls show Trump’s support is slipping among key groups, some showing him at a double-digit disadvantage to Democratic rival Joe Biden. Last Monday night, police and soldiers violently cleared protesters so Trump could walk from the White House to St John’s church for a photo opportunity. At that moment, Nolan Fuzzell had seen enough. Fuzzell is a table server at a restaurant in Lawrence, Kansas, and previously supported Trump. But after the photo stunt he tweeted: “Beginning to regret wearing all Trump gear on Election Day 2016. This is not right, on any level.”So how did Trump lose supporters like Fuzzell, and are they gone for good? It’s helpful to remember, first, what the president has asked of Republicans. He has treated the party like Theseus’s ancient ship, replacing one plank at a time until it becomes unrecognizable as itself. From a party whose elites sought to reject Trump in 2016, it has now become almost unerringly loyal and much changed. Under Trump’s leadership, Republicans have gone to war against their traditional allies, the FBI. They have cozied up to their old opponents, in Russia. Republican leaders have signed off on federal deficits so gargantuan – this year it will top a trillion dollars – they would make Franklin D Roosevelt blush. Trump adherents have had to boycott the reddest of American sports, professional football. Towering Republican heroes – political like Mitt Romney, military like John Kelly, both like John McCain – have come under Trump’s withering attack. Trump’s own former defense secretary, James Mattis, felt compelled to speak out against the treatment of American citizens during protests following the death of George Floyd at the hands of police. Comparing the president to Nazi propagandists, Mattis wrote: “We must reject and hold accountable those in office who would make a mockery of our constitution.”Among other things Trump has asked evangelical Christians, his staunchest allies, to overlook lurid descriptions of his sexual escapades, hush money paid to a porn actor and – with difficulty – the abandonment of vulnerable Christian communities in northern Syria. But the most difficult demand of Trump’s followers is unfolding now. For years, activists on the right railed against the possibility of US military deployment within the country’s borders. A conspiracy theory about such a program – called “Jade Helm 15” – grew so adamant that in 2015 Texas senator Ted Cruz requested an explanation from the Pentagon. It was a figment of the fevered rightwing imagination. But now, under Trump, the American self-invasion is coming true: squads of troops from agencies that normally oversee prisons, borders and drug enforcement have