With less than 40 days left until November's election, former President Donald Trump continues to escalate his personal attacks against Kamala Harris, calling for the vice president to be "impeached and prosecuted."

Throughout his campaign rally speech in Erie, Pennsylvania, on Sunday, Trump said Harris should be disqualified from running for president, resign from office and be investigated at the highest level.

"She should be disqualified. She should resign the vice presidency and go home to California," Trump told the cheering crowd while discussing the "invasion" at the U.S.-Mexico border.

While criticizing the Biden-Harris administration's immigration policies, Trump baselessly called for the Vice President to be impeached.

"She should be impeached and prosecuted for her actions," he said.

Trump has a long history of threatening legal action against his political rivals, including President Joe Biden, and Hillary Clinton in the run-up to the 2016 election.

Now, as he faces his own set of legal battles, the former president is again calling for investigations into his new opponent, Vice President Harris, over policies he disagrees with, attempting to blame her for the deaths of people killed by undocumented immigrants.

Harris visited the U.S.-Mexico border on Friday, her first trip there in more than three years.

Delivering a speech in Douglas, Arizona, a border town in the critical battleground state, Harris called for tougher security measures and criticized Trump for his role earlier this year in tanking a bipartisan bill that was the result of months of negotiations.

Harris' trip and Trump's continued comments on border security come as immigration continues to be a top issue for many voters ahead of the election.

A recent ABC News/Ipsos poll found that 70% viewed immigration at the southern border as an "important" issue for them, and Trump led Harris by 10 points on who voters thought was best suited to handle it.

However, as his Republican allies push for Trump to focus on the issues rather than attacking Harris, Trump’s rhetoric in recent days has become more extreme.

Trump's personal attacks on Harris Sunday echoed similar remarks from his rally on Saturday, where he called the vice president "mentally disabled."

"Crooked Joe became mentally impaired. 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," Trump said.

Majority Whip Tom Emmer, who is helping Sen. JD Vance with debate the vice presidential debate preparations, didn’t go as far as to rebuke Trump’s comments when pressed by ABC News’s Martha Raddatz; however, he did ultimately concede, "I think we should stick to the issues.”