At a press conference in New Jersey's Bedminster, the former US President said, "I don't have a lot of respect for her. I don't have a lot of respect for her intelligence. I think she'll be a terrible president. I think it's very important that we win. And whether the personal attacks are good or bad... she certainly attacks me personally."

Trump was responding to questions about his party members and colleagues urging him not to make personal attacks on Harris, the first woman of colour in the race to the White House.

"As far as the personal attacks, I'm very angry at her because of what she's done to the country. I'm very angry at her that she weaponised the justice system against me and other people. I'm very angry at her. I think I am entitled to personal attacks," he added.

The Republican presidential candidate said that Harris had "actually" called him and his running mate, JD Vance, weird. Defending Vance, Trump said that he's not weird, "He was a great student at Yale, he went to Ohio State, graduated in two years at the top of his class and all of these different things."

In fact, the former US President said that Harris was "weird in her policy," adding that "people don't know who she is yet."

"She is weird in her policy. Who wouldn't want to have strongholds, who doesn't want to have lower taxes? You know, all my life I've watched as politicians campaigned and I've always been on for the most part, on the other side," Trump said.

He said that this was the only campaign where he heard them saying that they were going to increase the taxes and "then people say they're going to vote for".

Trump also said that he didn't need to change his tone to win the Republican primary, noting that he was running a "very calm campaign" this time.

"I didn't rave and rant. I'm a very calm person," he said.

Early this week, several of Trump's colleagues and aides including his former White House aide Peter Navarro and former Republican candidate Vivek Ramaswamy, urged him to keep his focus on economy and policy instead of attacking Harris.

Former South Carolina Governor Nikki Haley had also said on Fox News this week that the Trump campaign needed to stop "whining".

"The campaign is not going to win talking about crowd sizes. It's not going to win talking about what race Kamala Harris is. It's not going to win talking about whether she's dumb... you can't win on those things. The American people are smart. Treat them like they're smart," Haley said.

Meanwhile, responding to Trump's conference, the Harris campaign issued a written statement on "whatever that was".

Harris campaign spokesperson James Singer said that the former President "huffed and puffed" while utilising "his usual lies and delusions", USA Today reported.