Ask someone to picture Bernie Sanders and they’ll likely see him leaning over a podium. With his arms raised. Shouting.

So the senator’s latest venture may seem a little jarring. It’s a chat show.

There have been four episodes of The Bernie Sanders Show so far, with the most popular seeing Sanders and his guest, Bill Nye, seated on stylish red armchairs. A coffee table is in front of them and shelves of hardback books line the wall behind.

Sanders has pages of notes resting on one knee. It could almost be a Sunday breakfast show.

But the genial settings shouldn’t fool anyone. Once the show gets under way, Sanders is typically brusque.

“Let’s cut right to it,” he tells Nye as he starts their conversation. We have a president who doesn’t believe in climate change, Sanders says. He asks Nye what this means for the environment.

The Bernie Sanders show, which is filmed in the Democratic party’s DC-based studio, is atypical in ways beyond just presentation. Sanders has decided to bypass traditional media and broadcast exclusively on Facebook. And it is attracting – to borrow a Sandersism – a huge audience.

The first episode of the show featured the Rev William Barber, a protestant minister and activist who is a national board member of the NAACP. The conversation, aired on 16 February, focussed on grassroots mobilizing, and has been viewed more than 950,000 times.

But it was the Nye broadcast that really got the Sanders’ team excited.

“That was the moment when we really saw the power of this. We got 75,000 people watching at the same time and it got over 4.5m views,” said Josh Miller-Lewis, Sanders’ deputy communications director.

It wasn’t just the viewing figures that were positive. Sanders is probably the most popular politician among millennials, and they let him know.

“Both Bill Nye and Bernie Sanders are amazing people! It gives me hope to see the two sitting down with each other talking about scientifically-informed public policy,” one person wrote.

“Today is my birthday and I wouldn’t wanna spend it any other way,” read another comment.

Various other people wanted to buy Sanders a beer, or indulge in other similarly relaxing pastimes.

The bulk of the audience is 18 to 45 years old – the sort of people who fueled Sanders’ presidential bid – and the show seems to have borrowed some of the fan imagery that emerged during that campaign.

The Bernie Sanders Show logo features a stencil outline of the top half of Sanders’ face in a style very similar to the Sanders tattoos that adorn many supporters bodies.

Miller-Lewis said Sanders himself is the brains behind much of the output.

“A lot of it’s Bernie to be honest. He is the creative source for this. All of the success that we have on social media stems from his message and it’s a powerful message that people respond to,” Miller-Lewis said.

“He’ll go through comments on his Facebook posts and talk with us about how people are responding, their reaction to certain policies, things they are struggling with in their lives.”

That information feeds into who Sanders invites onto the show, the issues he discusses, and his ambitious plans to take the show on the road.

Miller-Lewis said the senator plans to travel around the country bringing everyday folk on the program to talk about and highlight issues important to them. Planning is still in the early stages, but the tour is likely to begin with Sanders hosting fast food workers as a way to discuss the Fight for 15 campaign.

“Our goal – and this is all coming from the senator – is to find new ways to move outside the bubble of DC,” Miller-Lewis said.

“I think too often we get stuck in the debate and the discussions that are going on on the hill and in Congress. The senator really wants to find ways to go out and hear from real people in this country.”

Although Sanders’ use of Facebook as a way to directly reach his audience may be novel, the idea of a politician bypassing the mainstream media has been around for decades.

Nikki Usher, professor at George Washington university’s school of media and public affairs, said Franklin Delano Roosevelt started the trend with his radio “fireside chats” during the 1930s and 40s. John F Kennedy picked up the baton when he became the first president to fully embrace television – in part because he thought he could speak direct to the American public.

Barack Obama used broadcasts on the White House’s website, while Donald Trump has taken this to a new, albeit less polished, level with his Twitter use.

The scope of Sanders’ Facebook audience became clear after he used the platform to give a response to Trump’s state of the union speech in February. The video has 8.3m views, and statistics that Sanders’ office shared with the Guardian showed 80,000 people watched it live.

“We were essentially reaching as many people as we could if he went on cable news after the address,” Miller-Lewis said.

“But instead he was able to give a 15-minute speech about whatever he wanted. He didn’t have to deal with the questions that they were going to ask or the things the anchors on CNN thought were important.”

While that might be a boon for politicians, Usher said the rise of direct messaging is not necessarily a good thing for the public because it eliminates journalists as gatekeepers for policing potential misinformation.

“We know once misinformation or even just a part of an argument enters the public dialogue its really hard to correct misinformation,” Usher said. “I think it’s really concerning.”

While the show does allow Sanders to bypass questions from the media, Miller-Fox said it also enables him to learn from the public.

“He views social media as an incredibly important tool for talking to people, for communicating,” he said.

“He’ll go through comments on his Facebook posts and talk with us about how people are responding, their reaction to certain policies, things they are struggling with in their lives.”