Donald Trump has amplified insults and personal attacks against the Democrats' presumptive nominee Kamala Harris as they enter the final 100-day stretch of the US presidential elections.

In his latest public appearance during a campaign rally in Minnesota on Sunday (Philippine time), Trump mocked Harris' laugh, claiming that the media was trying to portray his opponent as the late British Prime Minister Margaret Thatcher.

He said, "It's not gonna happen" because "Margaret Thatcher didn’t laugh like that," as reported by CNN.

Trump has also painted Harris as an "ultra-liberal" who will "deliver crime, chaos, mayhem, and death to our country. I will restore law and order, justice in America."

He claimed if a "crazy liberal like Kamala Harris gets in, the American dream is dead."

"This November, the American people are going to reject Kamala Harris's crazy liberal extremism in a massive landslide," he said. "We're not going to let her turn the United States into communist San Francisco."

The day before, Trump appeared at a conservative Christian gathering in Florida, where he said that Harris had been a "bum" before becoming the standard bearer of the Democratic ticket.

He also said she was the "most incompetent, unpopular, and far-left vice president in American history."

A Harris spokeswoman responded to Trump's remarks by slamming the GOP nominee as a "bitter, unhinged, 78-year-old convicted felon."

"Trump has made his goals clear: he's determined to drag us backward, undermine our democracy, and enact his Project 2025 agenda to rip away our freedoms. But as he said tonight, 'a criminal is a criminal, they generally stay a criminal,'" the spokeswoman said.

"Voters will unite to reject the politics of hatred and division, grow the middle class, and make sure convicted criminal Donald Trump doesn't get anywhere near the White House," she added.