Former presidents Barack Obama and George W Bush have both criticised the current political climate in the United States in comments seen as indirect criticism of Donald Trump.
Mr Bush used a rare public address to discuss nationalism, racial divisions and Russia's intervention in the 2016 presidential election, all flashpoints of his fellow Republican's nine-month tenure in the White House, although he did not mention Mr Trump by name.
"Bullying and prejudice in our public life sets a national tone, provides permission for cruelty and bigotry, and compromises the moral education of children. The only way to pass along civic values is to first live up to them," Mr Bush said at the Bush Institute's National Forum on Freedom, Free Markets and Security on Thursday.
Mr Trump has used nicknames to demean opponents, such as "Crooked Hillary" for Democrat Hillary Clinton and, more recently, "Liddle" Bob Corker for a Republican senator who dared to challenge him.
Mr Bush, president from 2001 to 2009, emphasised the important role of immigrants and of international trade, two policy areas that Mr Trump has cracked down on while in office.
"We’ve seen nationalism distorted into nativism, forgotten the dynamism that immigration has always brought to America," he said.
"We see a fading confidence in the value of free markets and international trade, forgetting that conflict, instability, and poverty follow in the wake of protectionism."
Mr Obama, back on the campaign trail on Thursday for the first time since he left the White House in January, called on voters to reject a growing "politics of division" that he said was corroding American democracy.
Without mentioning Mr Trump by name, Mr Obama told campaign rallies in New Jersey and Virginia that voters could send a powerful message about the type of politics they want by backing Democrats in November 7 governor elections in the two states.
"What we can’t have is the same old politics of division that we have seen so many times before, that dates back centuries," Mr Obama told a cheering crowd in Newark, New Jersey, that chanted: "Four more years."
"Some of the politics we see now, we thought we put that to bed. That's folks looking 50 years back," Mr Obama said. "It's the 21st century, not the 19th century."
At a later stop in Richmond, Virginia, Mr Obama said modern politics increasingly did not reflect basic American values of inclusiveness and were driving people away from the process.
"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. Sometimes that feels frustrating," he said.
Many of Mr Obama's comments appeared to be thinly veiled swipes at Mr Trump, whose combative style and inflammatory rhetoric have led to frequent controversy and stoked political tensions.
A spokesman for Mr Bush said his remarks were formulated long in advance and echoed concerns he had discussed for years.
"The themes president Bush spoke about today are really the same themes he has spoken about for the last two decades," said Bush spokesman Freddy Ford.
Mr Bush touted US alliances abroad in his speech, something the current president has called into question, and he denounced white supremacy, which critics accused Mr Trump of failing to do quickly and explicitly earlier this year.
He said Americans were the heirs of Thomas Jefferson, the third US president, as well as civil rights leader Martin Luther King.
"This means that people of every race, religion, and ethnicity can be fully and equally American," Mr Bush said. "It means that bigotry or white supremacy in any form is blasphemy against the American creed."
He also described a decline in public confidence in US institutions and a paralysis in the governing class to address pressing needs.
"Discontent deepened and sharpened partisan conflicts. Bigotry seems emboldened. Our politics seems more vulnerable to conspiracy theories and outright fabrication," Mr Bush said. "We have seen our discourse degraded by casual cruelty."
Mr Trump has had a rocky relationship with the Bush family. He belittled former Florida governor Jeb Bush, who was an early opponent of Mr Trump for the Republican presidential nomination, and has criticised Mr Bush for the war in Iraq and for presiding over the September 11, 2001 attacks.
Bush said globalisation could not be wished away "any more than we could wish away the agricultural revolution or the industrial revolution".
He also had harsh words for Russia and seemed to take aim at Mr Trump for playing down Moscow's interference in the presidential election last year.
"According to our intelligence services, the Russian government has made a project of turning Americans against each other. This effort is broad, systematic and stealthy," he said.
"Foreign aggressions, including cyber-attacks, disinformation and financial influence, should not be downplayed or tolerated. This is a clear case where the strength of our democracy begins at home."