Former Presidents Barack Obama and George W Bush have voiced concern about the current political climate in the US, in comments seen as a veiled rebuke of Donald Trump’s leadership.
Mr Obama urged Americans to reject the politics of “division” and “fear”, while Mr Bush criticised “bullying and prejudice” in public life.
Both were speaking separately; neither mentioned President Trump by name.
Mr Trump, who has been critical of his two predecessors, is yet to comment.
Ex-presidents traditionally shy away from the political stage, and it was long considered in poor taste for a former occupant of the Oval Office to criticise one of his successors, the BBC’s North America reporter Anthony Zurcher says.
But norms and standards of behaviour that once seemed to be set in stone have fallen by the wayside in the current political environment, our reporter adds.
Speaking at a Democratic campaign event in Newark, New Jersey, Mr Obama said Americans should “send a message to the world that we are rejecting a politics of division, we are rejecting a politics of fear”.
He added: “What we can’t have is the same old politics of division that we have seen so many times before that dates back centuries.
“Some of the politics we see now, we thought we put that to bed. That’s folks looking 50 years back. It’s the 21st Century, not the 19th Century. Come on!”
He touched on similar themes at another event later in Richmond, Virginia, saying: “We’ve got folks who are deliberately trying to make folks angry, to demonise people who have different ideas, to get the base all riled up because it provides a short-term tactical advantage.”
Speaking just hours earlier in New York, Mr Bush said: “Bigotry seems emboldened. Our politics seems more vulnerable to conspiracy theories and outright fabrication.
“There are some signs that the intensity of support for democracy itself has waned – especially among the young.”
Americans, he said, have “seen our discourse degraded by casual cruelty”.
“At times it can seem like the forces pulling us apart are stronger than the forces binding us together.
“We’ve seen nationalism distorted into nativism, forgotten the dynamism that immigration has always brought to America.”
Both former presidents have until now largely avoided commenting publicly on Mr Trump’s policies.
by the BBC’s Gary O’Donoghue in Richmond, Virginia
President Barack Obama still knows how to draw a crowd – and they queued round the block for hours to see him speak.
But if they were hoping for head-on attacks on Donald Trump, they were to be disappointed.
However the criticisms when they came were scarcely veiled – with talk of pandering to the extremes and sowing divisiveness.
The speech followed a much more full-frontal attack on the current political situation by former Republican President George W Bush.
He talked about bigotry and falsehood threatening American democracy – while celebrating immigration and arguing for a more open trade policy.
These attacks certainly aren’t co-ordinated – but they do demonstrate just how widely concerns about the current president are shared.
President Trump has so far made no public comments in response.
Before his election last year, Mr Trump was highly critical of both Mr Obama and Mr Bush, describing each of them at one time or another as “perhaps the worst president in the history” of the US.
Since his inauguration in January, Mr Trump’s combative style and direct public comments on a number of key issues have caused controversy both among Democrats and Republicans.
He has regularly blamed the media, which he says do not focus on his achievements and instead choose to concentrate on what he describes as “fake news”.