Will Trump's unbridled rhetoric cost him the US election?

With his third straight U.S. presidential campaign coming down to the wire, Donald Trump mused at a rally about hydrogen-powered cars exploding, lamented how difficult it is to get spray paint off limestone and marveled at how billionaire backer Elon Musk's rocket had returned to Earth in one piece.

He complained Democratic rival Kamala Harris wasn't working as hard as he was, praised Chinese President Xi Jinping as "fierce" and called former President Barack Obama "a real jerk".

His aides had billed the event in battleground North Carolina as economy-focused, but that issue was just the warm-up.

In the countdown to the Nov. 5 election, the former president is campaigning in a way that some political commentators say could lose him precious votes against his Democratic rival, Harris, in what could be one of the tightest contests for the White House in history.

Surveys show the race is so tight that the result could hinge on a few thousand votes in several competitive states.

The Harris campaign is closing out its campaign by calling Trump "unstable" and "unhinged". She is increasingly embracing those terms and pointing to Trump's ramblings as evidence he isn't fit for the presidency.

Trump defends his scattershot approach by saying he does something he calls "the weave" – in which he claims he always returns to his initial point – and supporters say his unscripted style is part of his appeal.

"His patented weave is a brilliant method to convey important stories and explain policies that will help everyday Americans turn the page from the last four years of Kamala Harris' failures," said Steven Cheung, a spokesperson for Trump's campaign.

Trump's rallies have always featured their share of diversions and odd tangents. But with the clock ticking, the former president seems content to burn precious minutes telling stories about his White House days, musing about a dead athlete's penis size, going where his mind takes him.

"They gave Obama the Nobel Prize," he said on Thursday in Las Vegas. "He didn't even know why the hell he got it. He still doesn't. He got elected and they announced he's getting the Nobel Prize. I got elected in much bigger, better crazier election but they gave him the Nobel Prize."

Though no rally is ever exactly alike, a consistent theme is Trump's false assertion that in four short years Democrats have transformed the nation into a dystopian state.

He denounces his political opponents as the "enemy from within" and peppers his remarks with graphic accounts of murders and rapes of young women, false tales of violent gangs taking over small towns and debunked claims about immigrants eating stolen pets.

"We're like a garbage can for the world," he bemoaned in Arizona.

Trump aides say he sets the pace and talks as long as he wants. They don't try to contain him -- and they have put him in forums such as podcasts where his rambling ways can find a home and he won't be subjected to a battery of questions.

During a lengthy interview with podcaster Joe Rogan on Friday, Trump said that there may be life on Mars even though, as Rogan noted, probes have found no evidence.

He also claimed windmills have a negative effect on whales. The National Oceanic and Atmospheric Administration says there are no known links between large whale deaths and ongoing offshore wind activities.

"I want to be a whale psychiatrist," Trump said.

FRENETIC SCHEDULE, INDULGENT FLOURISHES

Trump has adopted a more frenetic campaign schedule with time growing short. Last week, he held events in six of the seven states likely to decide the election.

Talk of border security and crime dominated, but Trump always found time for indulgent flourishes.

On Wednesday in Duluth, Georgia, he went on an extended riff about how he averted a trade war with France over champagne. He spoke for so long that many in the arena began to leave.

Trump of late has been making headlines in ways that have nothing to do with how he would run the country.

He turned one rally into an impromptu dance party, swaying on stage to his favorite numbers for nearly 40 minutes. He shared a locker-room tale about the purported size of golfer Arnold Palmer's penis.

John Geer, an expert on public opinion at Vanderbilt University, said Trump's road show is aimed at one audience: his base.

"Trump thinks what he says, even if incoherent, appeals to his base," Geer said. "If he wanted to expand his coalition, he would not be engaged in random rhetoric."

The event before a crowd of about 7,500 people in Greensboro last week illustrated best how Trump is approaching his final days on the trail.

After talking about the border and restoring U.S. manufacturing, Trump bashed Harris for not campaigning that day and called her weak. He praised foreign strongmen such as Xi and Russia's Vladimir Putin, and mocked celebrities who had attended Harris' rallies: "These are not stars to me."

Trump then launched into a long tale about how he was on the phone earlier this month with a "very important guy" but was distracted watching TV footage of a SpaceX rocket returning to Earth.

"I see this 20-story huge tube pouring down, you know fires pouring out, and it used to be white, but the heat is thousands of degrees coming down. They say thousands and thousands, so it had been beat up on that trip down. And I see this massive tube is coming down and the fires burning and it's ... exploding all over the place," Trump said, motioning with his hands. "I said 'Oh, this is terrible. It's going to crash. What the hell is it?' I wasn't sure ... maybe it was a movie."

That led to a tangent where he compared his plan to exempt interest on car loans to the invention of the paper clip.

"It's very simple," Trump said. "Somebody came up with it 129 years ago or something. They came up with the paper clip. Then other people looked at it, they said, ... 'Why didn't I think of this idea?'"

At that point, Trump noticed how far he had veered off script. "I haven't looked at the teleprompter for 15 minutes," he boasted.