MIAMI (AP) — Former President Donald Trump on Tuesday reveled in the mounting turmoil surrounding President Joe Biden 's campaign in the wake of their debate and teased the expected announcement of his Republican running mate with one of the top contenders, Florida Sen. Marco Rubio, in attendance.

After days spent lying low, golfing and letting Democratic infighting play out in public, Trump used his return to the campaign trail in Florida to ratchet up his attacks on both Biden and Vice President Kamala Harris, indulging speculation that she could replace the president as the Democratic nominee this year and alleging, without evidence, that his son Hunter Biden is "running our government" and first lady Jill Biden "is helping." Biden has repeatedly insisted he won't withdraw from the race.

Trump rallied his supporters at one of his Miami-area golf courses as the presumptive Republican nominee nears a deadline to announce his running mate. But he appears in no rush, as much of the political world's attention is still centered on questions about Biden's ability to govern for another four-year term. Some Democrats have started calling for Biden to step down as their presumptive nominee following his dismal debate performance last month.

Trump, speaking from the 10th hole of his course, challenged Biden to another debate or even a "golf-off" reviving an offbeat argument from their debate. But mostly, he rubbed in how their meetup left Biden's campaign facing a grim prognosis.

"Our victory was so absolute that Joe's own party now wants him to throw in the towel and surrender the presidency after a single 90-minute performance," Trump said Tuesday night. "They want 'Crooked Joe' out of the race. It's a shame the way they're treating him. But don't feel sorry for him. He's a very bad guy."

James Singer, a spokesperson for Biden's campaign, responded to Trump with a series of challenges, saying in a statement: "We'd challenge Donald Trump to create jobs, but he lost 3 million. We'd challenge Donald Trump to stand up to Putin, but he bent the knee to him. We'd challenge Donald Trump to follow the law, but he breaks it."

Singer also said, "Joe Biden doesn't have time for Donald Trump's weird antics — he's busy leading America and defending the free world."

Trump laced into Harris with more specifics than usual. She has become a focus of the former president and his allies as speculation has mounted that she would replace Biden as the Democratic nominee. Trump called her "Laughing Kamala," and referred to the "Biden-Harris administration," rather than just pinning actions on Biden as he had for months, and blamed Harris for the White House's immigration policies.

"Despite all the Democrat panic this week, the truth is, it doesn't matter who they nominate because we are going to beat any one of them in thundering landslides and this November's going to be amazing," he said.

Trump, ever the showman, repeatedly played into the speculation that he might elevate Rubio to his ticket.

Rubio, a Miami native and one of the contenders for the vice presidential post, was among the Florida politicians who spoke at the event.

At one point, Trump marveled at the number of reporters in attendance and said, "I think they probably think I'm going to be announcing that Marco is going to be vice president."

Later, when he talked about his pledge to make tips tax-free, he remarked that Rubio "may or may not be there to vote for it."

Rubio, the son of Cuban immigrants, is seen as a potential running mate who could help Trump as he tries to secure support from Hispanic Americans, a point the senator emphasized in his remarks as he switched several times in his remarks to Spanish.

The senator did not openly acknowledge any of the speculation about him joining Trump as a running mate. He instead skewered not only Biden, whom he called "the figurehead of a left-wing government, shadow government," but Harris, whom he would need to debate head-on if he's chosen for Trump's ticket.

Rubio referred to Harris not by name at first but called her Biden's "replacement" and "a real-life, verified left-winger." At another point in his remarks, he mocked the way Harris laughs.

He notably seemed to insert himself into Trump's signature "Make America Great Again" slogan by saying: "Together, we're not just going to make it great again. We elect this man as president, we will make together America greater than it has ever been."

Thousands of people turned out in the humid summer evening for the rally. Attendees were fanning themselves and holding signs featuring Trump's mug shot, along with others that said, "You're fired!" — Trump's signature phrase on his former reality show, "The Apprentice."

Trump's youngest child who recently turned 18, Barron, also made his first-ever appearance at one of his father's rallies. Trump implored his son to stand, with the young man pumping his fist a few times as Trump said, "Welcome to the scene, Barron."

One attendee, 28-year-old Austin Stiglin, said he traveled from northern Florida to participate in his first Trump rally. He was wearing a star-patterned navy blue jacket and red pants and said he was "tired of the left telling him to vote left just because I am gay."

"I have a lot more to say than just my sexual orientation," Stiglin said. "I would like to vote for policies that support the United States."

Nicole Farrell, a 57-year-old immigrant from Trinidad, said she voted for Trump in 2020, "but I was not a strong supporter like now. I just preferred him over Biden."

Farrell said she specifically likes Trump's hardline immigration policies, which include plans for mass raids and the largest deportation operation in U.S. history.

"I am an immigrant but I came here legally. They need to come here legally," Farrell said of migrants coming to the U.S.

Both Biden, 81, and Trump, 78, are at least two decades older than most American presidents have been, according to the Pew Research Center, which said the median age for all U.S. presidents on their first inauguration is 55 years old. But that has not stopped Trump from arguing he is stronger than Biden, who repeatedly stumbled, paused and could not complete sentences at times during the June 27 debate. Trump was criticized by Democrats for making false statements during the debate about the Jan. 6, 2021, riot at the U.S. Capitol and suggesting immigrants entering the U.S. illegally were taking so-called "Black jobs" and "Hispanic jobs."

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Price reported from New York. Associated Press writers Zeke Miller in Washington and Jill Colvin in New York contributed to this report.