Trump criticizes Harris as he returns to the campaign trail in a transformed 2024 race

CHARLOTTE, N.C. - Former President Trump repeatedly took aim at Vice President Kamala Harris - his new opponent in the 2024 presidential election, as he returned to the campaign trail Wednesday with a stop in the crucial swing state of North Carolina.

"Now we have a new victim to defeat – lying Kamala Harris," the Republican presidential nominee charged at a large rally at an arena in Charlotte, the state's largest city.

The Republican presidential nominee is facing a dramatically altered 2024 race in his first rally since President Biden's blockbuster announcement Sunday that he was suspending his re-election bid and endorsing Harris to succeed him as the Democratic Party's standard-bearer.

The president's immediate backing of Harris ignited a surge of endorsements of Harris by Democratic governors, senators, House members and other party leaders. By Monday night, the vice president announced she'd locked up her party's nomination by landing the backing of a majority of the nearly 4,000 delegates to next month's Democratic National Convention. She also hauled in a staggering $100 million in the first 36 hours following Biden's announcement.

IT'S A MARGIN OF ERROR RACE BETWEEN TRUMP AND HARRIS 

And new polls conducted after Biden bowed out indicate a margin-of-error race between Harris and Trump.

The former president, pointing to the assassination attempt against him a week and a half ago, said "I was supposed to be nice. Something happened to me when I got shot. I got nice."

"If you don’t mind, I’m not going to be nice," Trump said to cheers from the crowd.

Trump quickly took aim at Harris, claiming she was "incompetent" and the "worst vice president in American history."

The former president also repeatedly worked to portray the vice president as a "radical left lunatic."

Trump argued that Harris is "more liberal than [Sen.] Bernie Sanders. Can you believe it."

Pointing to Biden's stunning announcement that came amid a growing chorus of calls from within the Democratic Party for him to drop out in the wake of his disastrous debate performance last month against Trump, the former president claimed "he quit because he was losing so badly in the polls."

Trump argued that the pressure by Democrats on Biden to suspend his re-election bid was "an undemocratic move" and charged that "these are nasty people, the Democrats."

Trump throughout the rally repeatedly criticized Harris over the surge of migrants over the nation's southern border during the Biden administration, claiming that "she’ll destroy our country if she’s elected, so we won’t let that happen."

Harris was tasked by Biden in 2021 with leading the diplomatic outreach to tackle the "root causes" of migration in the Northern Triangle countries. It led to her being dubbed the "border czar" by Republicans, although the White House has rejected that description.

The Biden administration has pinned the blame for the crisis on Republicans in Congress for not having approved funding and reforms to what it says is a "broken" system. Trump's comments helped spur congressional Republicans to vote against the measure.

The Harris campaign, responding to Trump, points to policies he implemented when in office, and recent placards calling for mass deportations at the Republican National Convention.

"The only ‘plan’ Donald Trump has to secure our border is ripping mothers from their children and a few xenophobic placards at the Republican National Convention. He tanked the toughest bipartisan border security deal in a generation because for Donald Trump, this has never been about actually securing the border – it’s always about himself. He can make up whatever lies he wants but the fact is there’s only one candidate in this race who will fight for real solutions to help secure our nation’s border, and that’s Vice President Harris," Harris campaign spokesperson Kevin Munoz said.

Harris is also turning up the volume against Trump. In a tease of her argument against the former president, Harris is pointing to her law enforcement resume as she spotlights Trump's legal controversies.

"As many of you know, before I was elected as vice president, before I was elected as a United States senator, I was the elected attorney general of California. Before that, I was a courtroom prosecutor. In those roles, I took on perpetrators of all kinds," Harris said Monday at an event at her campaign headquarters in Wilmington, Delaware.

"Predators who abused women, fraudsters who ripped off consumers, cheaters who broke the rules for their own gain. So, hear me when I say I know Donald Trump’s type," she emphasized as she pointed to Trump's multiple lawsuits and criminal cases, many of which are ongoing.

Harris repeated the line of attack the next day at a rally in Milwaukee, Wisconsin.

Trump responded on Wednesday, saying "I don’t think people are going to buy it."

He argued that the vice president "was one of the worst prosecutors in history" and that "she destroyed San Francisco."

Trump touted his support for law enforcement and landed the backing of the National Association of Police Organizations, as the group's president, Michael McHale, joined the former president on the podium to formally endorse the GOP nominee.

Ahead of the rally, Republican National Committee Chair Michael Whatley said even though Trump's now facing a new opponent at the top of the Democrats' ticket, the GOP's strategy "does not change … at all."

"We have been running our race, and we are going to continue to run our race," Whatley, a former North Carolina GOP chair whom Trump installed as RNC chair in March after clinching the Republican nomination, emphasized in a Fox News interview.

WHAT'S NEXT FOR HARRIS NOW THAT SHE'S SEEMINGLY LOCKED UP THE DEMOCRATIC NOMINATION?

Whatley, speaking at the rally site at Charlotte's Bojangles Coliseum, noted that Trump and the RNC will relentlessly tie Harris to Biden's polices on border security, fighting inflation, crime and other top issues in the 2024 election.

"The Democrats not only have a messenger problem, they have a message problem. And Kamala Harris is doubling down on every single one of Joe Biden's failed policies. It's the Biden-Harris administration, the Biden-Harris campaign. And she is picking up that mantle," Whatley argued.

The RNC chair emphasized Trump "has absolutely united the Republican Party in a way we haven't had in generations. Now it's time to unite the country around that vision of making America great again."

Trump narrowly won North Carolina in his 2020 election defeat to Biden, and Democrats see an opportunity to flip the state this November.

The trip by Trump to North Carolina is his second in two months. The last time Trump was in North Carolina, he was watching NASCAR in Concord over Memorial Day weekend. 

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The state is one of seven crucial battlegrounds that decided the 2020 contest and is likely to once again heavily influence the outcome of the 2024 presidential election.

"We continue to focus on the Blue Wall states of Michigan, Wisconsin, and Pennsylvania — and the Sun Belt states of North Carolina, Georgia, Arizona and Nevada, where the Vice President’s advantages with young voters, Black voters, and Latino voters will be important to our multiple pathways to 270 electoral votes," a memo from the Harris campaign said hours before Trump arrived in North Carolina.

Whatley said Trump, in his speech in North Carolina, needs to "continue his conversation with every American family, talking to every single American voter about his vision for a better America. He is going to be the one who is going to restore our southern border, restore our economy, restore our standing in the world and really be the one around that vision."

Fox News' Adam Shaw contributed to this story.

Get the latest updates from the 2024 campaign trail, exclusive interviews and more at our Fox News Digital election hub.