Elon Musk held his first solo event in support of Donald Trump for president on Thursday, encouraging voters in the Philadelphia suburbs to register to cast their ballots and vote early, though some attendees shouted back, “Why?”

The America PAC event at Ridley High School's auditorium in Folsom featured the world's richest man speaking onstage in front of a large U.S. flag for roughly 15 minutes before taking questions from the crowd, many of whom wore “Make America Great Again” hats.

The event was billed as a call to action to vote early in the crucial battleground state of Pennsylvania, where Trump and Democratic Vice President Kamala Harris are fiercely contesting the election. Some in the crowd questioned Musk's entreaties to vote early, reflecting the possibility that Republicans are still persuading their supporters to embrace early voting after Trump spent years demonizing the method.

The crowd rose to its feet and took cellphone videos as Musk, the billionaire founder of Tesla and Space X and owner of the social media platform X, walked onstage. They remained standing during his remarks and cheered loudly after he said the U.S. Constitution needs to be upheld.

“This is literally the fundamental values that made America what it is today. And anyone who is against those things is fundamentally anti-American and to hell with them,” said Musk, who was born in South Africa. The crowd erupted.

He exhorted the crowd to make sure they and their friends and family were registered to vote and to “pester” those who weren't. Toward the end of the question period, which included more than a dozen from those in the audience, he was asked to explain whether people should vote early in Pennsylvania. Musk was momentarily distracted by a fan waving a hat, which he appeared to sign, and then by a child whom he brought onstage for a photo.

Redirected to the question, he said people should vote immediately.

Read: Elon Musk commits $70 million to boost Donald Trump

Some in the crowd cupped their hands and shouted, “Why?” He did not answer. A spokesperson said after the event that he didn't have additional comment.

Trump for years has sowed doubt about mail and early voting by claiming it was rife with fraud, though voter fraud is rare in the United States. This year, Republicans are making a renewed push to encourage their supporters to vote early and lock in their ballots, though they acknowledge skepticism from those conditioned by Trump’s false claims.

John and Linda Bird, a couple who attended the event, said they had concerns about the integrity of the voting system and worried about voting early.

John Bird said he planned to vote on Election Day. Linda pointed to a sign given out at the event that said Trump called for early voting and worried about the possibility of not getting to the polls on Nov. 5.

Still, she said she'd cast her ballot on Election Day, too.

“Anything can happen, you know, you wake up that morning, some catastrophe happens or whatever,” she said. “But, you know, we’re planning on voting on Nov. 5.”

One of the questioners asked about fraud in elections — something Trump has falsely insisted cost him the 2020 race. An Associated Press review of every potential case of voter fraud in the six battleground states disputed by Trump found fewer than 475, a number that would have made no difference in the outcome.

Musk said sarcastically that it must be a coincidence that Dominion voting machines, which had been at the center of conspiracy theories in the 2020 election, were used in Philadelphia and Maricopa County, Arizona, located in two battleground states won by Democrat Joe Biden. In 2023, Fox News agreed to pay Dominion Voting Systems $787 million to avoid a trial in a defamation lawsuit the voting machine company brought against the network for lies told about their company switching ballots.

In an emailed statement Thursday, Dominion said its machines are not used in Philadelphia, as Musk said. The statement also said its systems are based on “verified paper ballots.”

"These are not matters of opinion. They are verifiable facts.” Dominion said.

Musk has become a major booster of Trump this campaign season. On Thursday evening, he cast the election in dire terms.

Read more: Trump's economic plans would worsen inflation, experts say

“I haven’t been politically active before. I’m politically active now because I think the future of America and the future of civilization is at stake,” he said.

People were lined up to attend before 3 p.m. as school was letting out. A few people began to leave early when it became clear that not everyone who had lined up to ask a question would have a chance to ask one.

The event was livestreamed on X, formerly Twitter, and was at times glitchy and difficult to follow, even as it drew hundreds of thousands of viewers.

Musk is undertaking much of the get-out-the-vote effort for Trump through his America PAC, a super PAC that can raise and spend unlimited sums of money. He has committed more than $70 million to the super PAC to help Trump and other Republicans win in November.

Trump and the Republican National Committee he controls opted for an unorthodox strategy of sharing canvassing duties in key regions with groups like Musk’s. They’ve also focused their efforts not on independent or moderate voters, but on those who already support Trump but usually don’t vote.

Republican activists in swing states said in September that they had seen little activity from the PAC’s get-out-the-vote efforts.