To attend a Trump rally in rural America makes you worry for humanity’s future. After six hours in the baking sun watching 60,000-plus Trump supporters lap up his lies, I am here to tell you that there are few more lowering experiences to be had in modern politics.

But it isn’t all we have, and there is much of a positive nature to report from the US, including an inspiring intervention from Barack Obama last week and the truth that the Democrat candidate for presidency, Kamala Harris, is conducting a very good campaign indeed. Given that she’s had just three months to pick her running mate, coordinate strategy and key messaging, and confront a wretchedly divided nation, she’s performing with grace and steadiness, while the campaign has united around building a coalition with disaffected Republicans and conservatives of conscience who were in Congress or the Trump administration.

For the first time since July, when Harris became the Democrat candidate, the New York Times/Siena College poll shows her leading Trump by three points, 49-46. In the average maintained by The Hill website she is showing a lead of 3.4. Sure, both are within the margin of error and the contest in the seven swing states is much tighter, but the trends are in her favour. She is improving on the key issues of economy and migration and is becoming the candidate of change.

A persistent Maga attack line over the last months was that she was too scared, ignorant or dumb to do interviews. She answered it by sitting down with Alex Cooper’s Call Her Daddy podcast, giving a fascinating interview to Howard Stern’s radio show, sharing a beer with Stephen Colbert on his late-night show, and announcing, on Whoopi Goldberg’s The View that, if she won, Medicare would pay for home care. Finally, she faced the remorseless Bill Whitaker in the 60 Minutes interview, an October ordeal for presidential candidates for the last 50 years. She carried herself well and was never less than poised. As I wrote in this paper, I once spent a few hours with her at a social event and liked her a lot but, after seeing those five shows, I feel a duty to note that she can be extraordinarily slippery when it comes to answering questions.

Yet she is abiding by all the rules of the democratic game, unlike Donald Trump who refuses to engage in the process and tours his own rallies, ranting and lying, and looking somehow more lumpen and angrier than ever before. Naturally, he pulled out of the 60 Minutes interview, first saying that he didn’t want to be fact checked, then demanding an apology from his previous interviewer Lesley Stahl for something she hadn’t done. There was a fuss about the edit of the Harris programme, which Maga claimed showed the vice-president in a favourable light – it didn’t – but before that got traction the news moved on with two newspaper articles.

The New York Times ran a story logging Trump’s mental decline, then, seemingly to prove its point, Trump took himself to the swing state of Michigan last Thursday and trashed the city of Detroit in a speech to, yes, the Detroit Economic Club. The Washington Post published exclusives from Bob Woodward’s new book War that revealed that Trump sent Covid tests to Putin and had spoken to him from Mar-a-Lago, the country club where he was alleged to have kept stolen secret documents in a bathroom. The most delightful revelation was a quote from Republican senator Lindsey Graham. “Going to Mar-a-Lago is like being in North Korea. Everybody stands up and claps every time Trump comes in.” One further positive note. Harris has pulled in over $1bn in campaign donations and is outspending Trump on social media, which is smart because 16 million young people have joined the electorate since 2020. Latest figures show she’s spent $57m with Meta, owner of Facebook and Instagram, to Trump’s $6m, and on Google, owner of YouTube, $31.5m compared with Trump’s $9.3m.

I spent the week in the state of Pennsylvania, which is the epicentre of the race because it has 19 electoral college votes – the most of any swing state. If a candidate wins by just a handful of individual ballots, he or she will take all the state’s 19 electoral college votes, and probably go on to win the White House.

The race is effectively tied and both candidates are putting enormous effort into the state. Trump appeared there twice last week, most theatrically at a big rally in the western town of Butler, 35 miles from Pittsburgh, and where he was winged by a would-be assassin three months ago. It was a triumphant return, with much fanfare and many turns and speakers, including JD Vance and a goofy-looking Elon Musk in “dark” Maga cap. Halfway between a revivalist meeting and a country fair, the event told me a lot about the Maga cult but nothing about politics or Trump’s plans (Project 2025 is never mentioned). However, I did establish the truth of rumours that hundreds of people leave his rallies as soon as he starts speaking.

Last Wednesday, the splendidly principled conservative politician Liz Cheney, who appeared briefly with Harris on 60 Minutes after endorsing her, hosted a session at Glenside, Pennsylvania, with three female former staffers in the Trump White House who provided insights into Trump’s character and the chaos he brought to every issue and situation. This was peripheral to the main campaign but the impact of coherent and respected Republicans speaking against Trump may bring critical votes to Harris. Every vote matters. “Don’t boo,” Obama routinely says, “Vote!”

Obama made his first appearance for Harris in Pittsburgh, last Thursday, reclaiming the territory in western Pennsylvania from the Trump rally five days before. The speech was among the best he’s ever given, ranking among his appeals to the American public during the 2008 presidential campaign and the wonderful acceptance speech I saw him make in Chicago. He teased Trump remorselessly, mocking his lies, the obsession with money, power and status and his “concepts of a plan”. He imagined Trump doing something normal like changing a tyre or a nappy. Someone in the audience shouted out, “his own”. Obama smiled and said he’d thought of that joke but resisted the temptation. This drives Trump and Maga to distraction because, like all those with fascist leanings, they cannot stand people making fun of them. Humour will be an important weapon in the next 23 days because the Democrats need to get under his skin and provoke him to show his truly toxic, bullying nature.

Obama’s speech was important for its moral indignation, and it may just be the start of national rejection of Trump’s lies, a kind of have-you-no-sense-of-decency moment that recalls the time in 1954 when a lawyer named Joseph Welch stood up to Joe McCarthy and ended his communist witch-hunt. It could be that Trump and Maga have overreached themselves with their lies about emergency funding after Hurricane Helene ripped through the south-west causing destruction and hundreds of deaths; in one case a family of 11 was wiped out in a mudslide.

According to Obama: “Donald Trump just started making up stories about the Biden administration withholding aid from Republican areas and siphoning off aid to give to immigrants… you’ve got a guy who lies to score political points. I want to ask Republicans out there, when did that become OK? Why would we go along with that?”

Obama is practically the only person in America who has the moral authority to make this speech. He and his wife, Michelle, are still the most popular and trusted public figures in the country. Republicans will listen to him because, despite the last nine years, ideas of decency and service still have a potent appeal here.

What do I think will happen? I agree with the Democrat activist I met in Philadelphia who said: “We’re winning, but we haven’t won yet.” It’s all to play for and in Harris the Democrats have an authentic and tireless candidate who would do the best job she could in the White House.

But let me just warn that even if she wins on 5 November, Trump will not accept defeat. There is evidence that Republicans are building a case to challenge the result by manipulating the late polls in his favour so that any Democrat victory looks like a steal. There will be months of dispute, agonising waits and, I am afraid, intolerable anxiety for us all. But, as Obama says: “We gotta keep hoping.”