Former US Presidents Barack Obama and George W Bush expressed concern about the current political climate in the country, in comments seen as a veiled rebuke of Donald Trump's leadership.
Obama urged Americans to reject the politics of division and fear, while Bush criticised "bullying and prejudice" in public life.
They were speaking separately. Neither mentioned President Trump by name. Trump, who is critical of his two predecessors, is yet to comment, reports BBC on Friday.
Former US presidents traditionally shy away from commenting publicly on their successors. Obama had said on leaving office he would extend that courtesy for a time to Trump, as George W Bush had to him.
He has broken his silence since to issue statements on Trump's efforts to dismantle Obamacare, as well as his controversial "Muslim ban" and decision to abandon the Paris climate accord.
Speaking at a Democratic campaign event in Newark, New Jersey, 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!"
Speaking just hours earlier in New York, 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, "seen our discourse degraded by casual cruelty".
