Barack Obama has said it will take more than one election to reverse a culture of “crazy conspiracy theories” in US politics.
The former president, 59, said the nation was more divided today than it was when he was elected to the White House in 2008.
He suggested Democratic president-elect Joe Biden’s victory was only the first step in repairing divisions that had been “fanned” by Donald Trump.
In an interview with the BBC to promote his new memoir A Promised Land, Mr Obama said: “We are very divided right now, certainly more than we were when I first ran for office in 2007 and won the presidency in 2008, even more than when I ran for reelection in 2012, more divided than we were four years ago when Donald Trump first won the presidency.
“And some of that is attributable to our current president who actively fanned division because he felt it was good for his politics, but it preceded him and it will outlast him.
“ I discuss in the book some of the trends that have created that kind of division.”
Mr Obama told the historian and presenter David Olusoga that a growing divide between rural and urban areas, immigration and a polarised media landscape had led to “truth decay”.
Outlets such as Fox News and voices such as the conservative broadcaster Rush Limbaugh had contributed to the issue, he suggested.
Mr Obama continued: “I think the debate that has been taking place here about the kinds of crazy conspiracy theories and what some have called truth decay where facts don’t matter, everything is fair game, everything goes, that has contributed enormously to these divisions. It’s going to take more than one election to reverse those trends.
“It is going to require work at a local level as well as well as on a national level.
“It is going to require not just political work but cultural work to get people to listen to each other, think more critically and evaluate information.
“I think at some point it is going to require a combination of regulation and standards within industries to get us back to the point where we at least recognise a common set of facts before we start arguing about what to do with those facts.”
During the interview, Mr Obama appeared to address the conspiracy theory that Hillary Clinton was involved in a paedophile ring run out of a Washington pizza restaurant.
He said: “There are millions of people who subscribed to the notion that Joe Biden is a socialist, who subscribed to the notion that Hillary Clinton was part of an evil cabal that was involved in paedophile rings.”
Barack Obama Talks To David Olusoga airs on November 18 at 7.30pm on BBC One and was commissioned by BBC Arts.