Hillary Clinton has accused Donald Trump of unleashing an "incredibly dangerous" level of hate and vitriol that makes her "worried as an American".
The former Democratic presidential nominee and US first lady lashed out at the Republican president as she reflected on the 2016 election campaign during an appearance at a book industry conference in New York City on Thursday.
Mrs Clinton said Mr Trump encouraged his supporters to express their anger verbally and physically during the campaign, a reference to multiple incidents of violence at Trump rallies.
She likened the president's strategy to that of leaders in Bosnia and Rwanda who inflamed cultural tensions to win power.
"That is incredibly dangerous," she said.
"That is unleashing a level of vitriol, and defensiveness, hatred, that I don't think we should tolerate."
Mrs Clinton cited the recent attack in Portland, Oregon, in which two people were killed after confronting someone shouting anti-Muslim insults at two young women.
Mr Trump called the violence "unacceptable" two days after the attacks.
"The victims were standing up to hate and intolerance," he said on Twitter .
Mrs Clinton did not mention her explosive comments from a day earlier in which she blamed her election loss on various factors.
Among them, she said she inherited "nothing" from the Democratic Party and that the press had overreacted to her use of a private email server while she was secretary of state.
Last month, she also attributed her loss to misogyny, Russian interference and questionable decisions by the FBI.
Mr Trump elevated Mrs Clinton's comments by tweeting late on Wednesday: "Crooked Hillary Clinton now blames everybody but herself, refuses to say she was a terrible candidate."
Mrs Clinton said on Thursday that she feared Mr Trump may already be doing "lasting damage" to US institutions.
"I'm fine as a person," she said of her loss, "but I'm worried as an American".