Donald Trump’s presidency may be well and truly over but the fake news and conspiracy theories that dominated it are now roiling Joe Biden’s first months in office.

This week, President Biden did something unremarkable.

While walking on the south lawn of the White House he stopped to field questions from reporters.

“Do you have any plans to travel to the southern border?” one journalist asked.

“Not at the moment,” Biden said. He answered another question about COVID-19 vaccines before walking away.

Within hours, parts of the internet were ablaze with conspiracies that the interview was a fraud and the President was actually acting in front of a green screen.

Peddlers of the theory point to Biden’s hands appearing to fall over and pass through the reporters’ microphones.

Journalists at the press conference came out in droves to confirm it did actually happen, and Facebook has been working to remove the video from its site.

But a YouTube video titled “Biden fakes interview, green screen fails” has now been viewed by more than half a million people.

Tweet from @thehill

“For those asking. Biden walking to the helicopter is real. The ‘reporters’ being there? That’s fake,” writes the popular right-wing account that uploaded the video.

It’s not the only hoax – videos of Biden with slowed-down speech or forgetting which state he was speaking in have been going viral since he first began his campaign for the White House.

It’s easy to dismiss these videos as crazy conspiracies, but they have real-world impacts, said United States Study Centre research associate Elliott Brennan.

“The bar for influencing politics has never been lower. It’s quite simple to do, and some of the distorted videos have ended up dominating headlines for weeks,” said Mr Brennan.

The power is in how far they spread and distort the truth, he said.

“Something that’s central to democracy in Australia and the US is the value of truth. Once you have questions of legitimacy flying around an elected leader, it’s immensely damaging to that country,” he said.

“The degradation of truth is a very serious issue and something we’ve seen exacerbated in  the last five years.”

He pointed to January 6, when Trump supporters swarmed Capitol Hill, and Pizza Gate as real-world incidents inspired by conspiracies that grew online.

“The online world has evolved faster than we can keep up with,”  Mr Brennan said.

“How we handle it is an enormous question. It’s a question for the tech companies who have been hosting it.”

As President Biden starts to roll out his economic relief package and fights to turn the tide on the spread of the pandemic in the US he will also be fighting to control the narrative, said Australian National University professor Wesley Widmaier.

“I think with Clinton, Gore and Obama, there was this naive thinking you could just do better, you’d be rewarded at the polls,” Professor Widmaier said.

“That’s not what politics is – you have to have a narrative.”

President Biden needs to leverage not just his policies but his personality to hose down conspiracy theories and unite a divided country, he said.

“The hearts matter more than minds. Trump had an emotional connection with people and Biden will need one too.”