Trump’s rally in Pennsylvania took on similar themes to an event the day before that he himself described as a ‘dark speech’.

Republican presidential nominee Donald Trump has escalated his personal attacks on his Democratic rival, Kamala Harris, by repeating an insult that she was “mentally impaired” while also saying she should be “impeached and prosecuted”.

Trump’s rally on Sunday in Erie, Pennsylvania, took on similar themes as an event the day before that he described as a “dark speech”. He claimed in front of a cheering crowd on Sunday that Harris was responsible for an “invasion” at the United States-Mexico border and told them “she should be impeached and prosecuted for her actions”.

“Crooked Joe Biden became mentally impaired,” he added. “Sad. But lying Kamala Harris, honestly, I believe she was born that way. There’s something wrong with Kamala. And I just don’t know what it is, but there is definitely something missing. And you know what, everybody knows it.”

With about a month until the election, Trump is intensifying his use of personal and offensive attacks, even as some Republicans say he would be better off sticking to the issues that concern voters.

Trump has long threatened legal action against his rivals, including President Joe Biden and his 2016 rival, Hillary Clinton.

Trump has many legal problems of his own. He was convicted in May of falsifying business records in a hush money case in New York, with sentencing scheduled for November 26. Two other cases are pending – a federal case for his alleged role in the January 6, 2021, insurrection, and a state case in Georgia for his efforts to overturn his 2020 loss there to Biden. Prosecutors are appealing against a federal judge’s dismissal of a case involving his handling of classified documents.

Trump argues federal and state prosecutors are targeting him for political reasons. There is no evidence to suggest that is true.

On Sunday, Trump acknowledged he might lose in November: “If she wins, it’s not going to be so pleasant for me, but I don’t care.”

Trump has derided Harris, the first Black woman and person of South Asian descent to lead a major party ticket, as “stupid”, “weak”, “dumb as a rock” and “lazy”. His allies have pushed him publicly and privately to talk instead about the economy, immigration and other issues.

“I just think the better course to take is to prosecute the case that her policies are destroying the country,” Senator Lindsey Graham told CNN’s State of the Union programme on Sunday when asked about Trump’s comments, describing Harris’s policies as “crazy liberal”.

When asked whether he approved of Trump’s personal attacks on Harris, Republican Tom Emmer sidestepped the question during an interview on ABC’s This Week.

“I think Kamala Harris is the wrong choice for America,” said Emmer, who is helping Trump’s running mate JD Vance prepare for Tuesday’s vice presidential debate. “I think Kamala Harris is actually as bad or worse as the administration that we’ve witnessed for the last four years.”

When pressed, Emmer said: “I think we should stick to the issues. The issues are – Donald Trump fixed it once – they broke it. He’s going to fix it again. Those are the issues.”

Harris has not commented on Trump’s recent attacks but has said when asked about other comments that it was the “same old show. The same tired playbook we’ve heard for years with no plan on how he would address the needs of the American people.”