Barack Obama and George W Bush warned last night that USA democracy was succumbing to division in remarks seen as veiled rebukes to President Trump.
Last year, Bush supported the unsuccessful presidential campaign of his brother, former Florida Governor Jeb Bush, one of a large field of Republican contenders Trump defeated for the party's presidential nomination before winning the November election. "The only way to pass along civic values is to first live up to them".
"We've seen our discourse degraded by casual cruelty", Bush told attendees of a Bush Institute forum entitled "The Spirit of Liberty: At Home, In the World".
"Politics are now about discrediting people by ad hominem attacks, not by argumentation", Eliot Cohen said.
"At times it can seem like the forces pulling us apart are stronger than the forces binding us together", Bush said.
Mr Bush delivered a searing verdict on the nationalist ethos that animated Mr Trump's campaign, urging America to turn its back on a resurgence of white supremacism. "The great democracies face new and serious threats yet seem to be losing confidence in their own calling and competence", Bush said in New York City. "Disagreement escalates into dehumanization".
Mr Bush, 71, had used his speech a few days ago to warn white supremacy and falsehoods were coarsening the tone of the USA and threatening its democracy.
Separately, Mr Obama said that the political climate was "infecting" communities with a politics of fear consigned to a past era.
Speaking at the Bush Institute's Spirit of Liberty event in NY, the 43rd president warned against the isolationism and trade protectionism that Trump has long espoused. "Too often, we judge other groups by their worst examples while judging ourselves by our best intentions".
"Our identity as a nation, unlike other nations, is not determined by geography or ethnicity, by soil or blood", Bush said Thursday. "You won't be able to unite them later if that's how you start".
He added, "We have seen nationalism distorted into nativism".
The former president also made an oblique reference to Trump's claim this past summer that both sides were to blame following white supremacist violence in Charlottesville, Va. "Bigotry or white supremacy in any form is blasphemy against the American creed", Bush said.
The former president noted that Americans are the heirs of Thomas Jefferson, the third USA president, as well as civil rights leader Martin Luther King, Jr.