First came “joy”, with some cosy but unmemorable TV sit-downs with sympathetic hosts, a Vogue cover, and a billion dollars to spend on TV ads. Then reality hit: Kamala Harris’ strategy to win over a mysterious sliver of undecided US voters was not working and she was slipping back in the polls.

So the vice president went on Fox News, part of a pitch to white working-class women, who voted for Trump more strongly in 2020 than 2016. It was a win for Fox’s news division – 7.8m viewers, or four times host Bret Baier’s nightly average – but was it a win for the Harris campaign?

Showing herself to be assertive, Harris avoided serving up a unintelligible word salad, pushed back on Baier’s line of questioning, aired some Democratic talking points, and ran down the clock until the 25-minute slot was up.

“Let me be very clear, my presidency will not be a continuation of Joe Biden’s presidency,” Harris said. “I represent a new generation of leadership. I, for example, am someone who has not spent the majority of my career in Washington DC.”

Then the spin machine started up: according to Democrat voices, Fox News had helped Harris win November’s election. “I think she had a mission she wanted to do and maybe she wanted to have a viral moment,” Baier later said. “And I think she may have gotten that.”

But Fox’s primetime opinion hosts spent three subsequent hours eviscerating her. Donald Trump congratulated Baier “on a tough but very fair interview, one that clearly showed how totally incompetent Kamala is”.

With $15bn spent on this election cycle, the candidates are still grasping for a campaign formula that will give them an edge. Harris has evolved from being interview-shy to embracing an interview blitz. She followed other Democrats on to Fox News because that’s where, the theory goes, independent and Trump-neutral Republican voters are.

But will any of it matter? There are no guarantees that undecided or unengaged voters today will be any less undecided in two-and-a-half weeks’ time.

“You want to go on places like Fox where you might be able to talk to people who aren’t already in your corner,” says media professor Bob Thompson at Syracuse University. “If you do a good job, it’s a rational strategy. But I’m not sure that’s how it plays out in an irrational world.”

University of Virginia political scientist Larry Sabato says what was important was that she survived. “There were no big gaffes in there, and she managed to upbraid the interviewer. Did it affect anything? No. It’s just part of the daily gruel of a campaign. It doesn’t switch millions of votes or even thousands of votes.”

TV interviews, however hostile, have formed a key part of presidential campaigns for as long as television has existed. The bigger shift in Harris’s media strategy has been her embrace of podcasts.

Harris went on Call Her Daddy, a highly successful female empowerment podcast, and also spoke to shock-jock originator Howard Stern, where they talked about their love of Prince. Then she appeared on Charlamagne Tha God, a popular Black radio show, to court young Black voters – a major concern of Democrats – and to brush off criticism that she comes off as “very scripted”. Harris agreed with the radio host that Trump was a fascist.

It’s a strategy that’s been dubbed “podcast populism” – and it’s one that Trump has leaned into as well.

In recent weeks, Trump has been on a blitz of eight podcasts – online shows popular with male audiences – that produced a stream of viral moments.

He went on Full Send, Bussin’ With the Boys, PBD Podcast (to reiterate his belief that a lot of people were not aware that Harris is Black), before also sitting down with Andrew Schulz on Flagrant. With Theo Von, a quirky young redneck podcaster, the host discussed go karts, cocaine and Big Pharma. Trump talked about his brother’s alcoholism.

Von and Schulz are two of the biggest stars of pod-world, each resistant to political correctness and conventional political wisdom. Both candidates are reportedly open to going on Joe Rogan, whose podcast is second only to Call Her Daddy and has an audience 30 times bigger than CNN, even before it’s filleted and shared exponentially on social media.

So with less than three weeks left, who got it right?

Trump is largely avoiding the mainstream media, which he has long criticised as a purveyor of fake news, and Harris is visiting audiences across the political spectrum.

Trump is focused on mobilising friendly voters, while Harris is looking to win over voters who remain undecided about her.

Michael Morris, a Columbia university professor of leadership, argues in a new book, Tribal, that it is imperative to understand the pervasive influence of tribalism in contemporary politics to comprehend the uphill battle both candidates have in establishing an advantage.

“The idea that some sort of tribal drive to hate outsiders has atavistically reawakened [people] and now the genie can’t be put back into the bottle, and democracy is over … makes for good stories – but not good policy,” he says. Morris argues that political disagreement comes from a conformist instinct because we absorb opinions from the people and signals we spent time around. Over the past few decades, US liberals moved to the coastal cities and conservatives to the suburbs and heartlands.

“Each became accustomed to form different understandings of factual matters that then make us distrust the other side, become baffled and distrust that they believe the things they say are sincere,” Morris says. “Partisanship is a byproduct of the way we process information.”

Interviews with candidates on perceived liberal or conservative corporate media that the viewer already distrusts achieve little, he argues. But podcasts can be different.

“The podcast medium creates the illusion that someone from the other side is really just a friend of a friend – a chat with someone you trust,” says Morris, noting that the listener is not so confronted – they may be commuting or working out on a treadmill.

“Trump’s conversation with Theo Von made him seem like a real person and sound empathetic,” he says. Harris’s conversation with Howard Stern, he adds, had a similar effect. “She’s not seemingly like a leader from the other side – she’s just Howard’s conversation partner, and they trust Howard.”

Under those circumstances, the candidates are less like arch enemies. “Perhaps your mind is more open, and tribal psychology helps us understand that.”