WASHINGTON − Former President Donald Trump returned to the campaign trail Tuesday and mockingly challenged President Joe Biden to another debate in the wake of the president’s rocky performance last month.

Taunting Democrats who want Biden to drop out and allow Vice President Kamala Harris or another Democrat to enter the ring, Trump said during a sweltering Florida campaign stop he would give the incumbent president a chance to “redeem himself” with another debate − this week.

“This time it will be man-to-man − no moderators, no holds barred,” Trump told Florida supporters gathered at the Trump National Doral Golf Club Miami.

Biden and Trump have already agreed to a Sept. 10 debate to be sponsored by ABC News.

But Trump didn’t only bash Biden and Harris during the Florida rally. He also again used dehumanizing language about undocumented immigrants as he laid out his border priorities for a second term. Trump has long vowed mass deportations across the country if he returns to the White House, and border debates have taken center stage during his third White House bid.

Here are four key takeaways from Trump’s Florida campaign rally.

Bashing Biden while he’s down

Trump, who has laid low in recent days as Democrats debated Biden’s age and mental fitness, sought to take full advantage of concerns from Democratic voters and lawmakers.

Trump accused Biden of being a “part-time president” in front of his crowd of supporters after his 2024 rival struggled to articulate his pitch to Americans on the debate stage. During his speech, Trump said his opponents are “having a full-scale breakdown” because “they can’t decide which of their candidates is more unfit to be president,” Biden or Harris.

Several Democrats in Congress have suggested that Biden withdraw, fearing that his falling poll numbers will take them all down on Election Day. Biden has said that Democratic disunity is the bigger threat, and he has urged the party to stick with him.

A CBS/You Gov national survey conducted in the days after the debate found that 72% of voters do not believe Biden has the mental or cognitive health to serve as president, as well as nearly half of his own party. That was up seven points from the beginning of June.  

The Biden campaign said Trump’s debate proposal was not serious, only part of a performance that included extended comments about golf and references to fictional serial killer Hannibal Lecter. Trump during his speech made fun of Biden by challenging him to a golf match at Doral.

“Joe Biden doesn’t have time for Donald Trump’s weird antics – he’s busy leading America and defending the free world,” said Biden spokesperson James Singer.

Targeting Harris, just in case

Trump, who said Monday that Biden may well hang on to the nomination, spent most of the Florida rally attacking the incumbent − but also found time to go after his potential replacement, Harris.

At one point, Trump claimed that some Democrats would be reluctant to elevate Harris − and that’s why Biden picked her in the first place. “The best insurance policy I’ve ever seen,” Trump said.

During a campaign event earlier in the day on Tuesday in Las Vegas, Harris knocked the former president, alleging that he “wants to turn our democracy into a dictatorship.”

A poll conducted last week by the firm Bendixen & Amandi Inc. showed that Harris could narrowly beat Trump in November. In the national survey conducted by the Democratic pollster, she would edge out Trump, 42% – 41%. The survey showed 12% undecided and 3% support going to third-party candidates.

Attacking undocumented immigrants

Trump also noted that Biden tapped Harris earlier in his administration to take on an issue that’s at the heart of the presidential campaign: The southern border.

Repeatedly assailing illegal border crossings and falsely accusing migrants of widely committing crimes, Trump said immigration will be a top issue regardless of his opponent.

It’s not the first time in recent months Trump has used the rhetoric against migrants. Trump told crowds in June that he that he has floated the idea of a migrant fight club to UFC President Dana White, calling immigrants to the United States “nasty” and “mean.”

Trump also told a New Hampshire crowd last year that immigrants who enter the U.S. illegally are “poisoning the blood of our country.” A 2019 USA Today analysis of more than five dozen of the former president’s rallies found he had used words like ‘invasion’ and ‘killer’ to discuss immigrants at rallies 500 times.

Sidestepping the running mate search

Trump also staged his Florida rally as he prepares to announce his running mate. It featured one of the top contenders: Sen. Marco Rubio, R-Fla.

The former president made several positive references to Rubio during the speech, noting at one point that the two of them played rough during the 2016 Republican primaries. “We had a vicious campaign for a while,” Trump said of the former opponent he once called “Little Marco.”

During that campaign, Rubio called Trump a “con man” with “small hands,” but he became more supportive after Trump won the White House.

During the rally, Trump joked about Rubio’s chances to be the running mate, noting that his proposal to eliminate taxes on tips would need Senate approval: “You may or may not be there to vote for it.” 

Other vice presidential contenders include Ohio Sen. J.D. Vance and North Dakota Gov. Doug Burgum.

Trump said he may announce his decision just before or during the Republican convention, which opens Monday in Milwaukee.

Contributing: Karissa Waddick, Rachel Barber and Francesca Chambers, USA TODAY