Elon Musk, a harsh critic of illegal immigrants, spent the latter part of Sunday trying to refute claims from President Joe Biden that he once worked illegally in the United States.
Musk, born and raised in South Africa, denies the allegation.
The Washington Post reported that Musk worked illegally in the country while on a student visa.
"That wealthiest man in the world turned out to be an illegal worker here," Biden told a union hall in Pittsburgh while on the campaign trail for Kamala Harris. "No, I'm serious. He was supposed to be in school when he came on a student visa. He wasn't in school. He was violating the law. And he's talking about all these illegals coming our way?"
The president is an advocate for immigration reform, providing green card plans for immigrant spouses and implementing a series of executive actions that restrict asylum claims for migrants crossing illegally.
The newspaper claimed that upon arrival in Palo Alto, California in 1995 to work in a graduate program he chose not to.
The investigation said Musk once admitted that he "had no legal right to stay in the country."
Citing company documents, former business associates and court documents, although Musk arrived in the U.S. for a graduate program at Stanford University, he "never enrolled in courses, working instead on his startup." When he finally applied to the school, it was so he could continue to work in the States legally.
Musk wrote on X in reply to a video post of Biden's comments: "I was in fact allowed to work in the US." Musk added, "The Biden puppet is lying."
Investors in Musk's company, Zip2 (which was initially called Global Link Information Network), were concerned about the possibility of their founder being "deported" the report claimed. One board member said his immigration status "was not what it should be" for him "to be legally employed running a company in the U.S."
The expose referenced a 2005 email from Musk to his Tesla associates acknowledging that he did not have authorization to be in the country when he started Zip2.
The world's wealthiest man whose en route to becoming the first trillionaire, came out swinging against the claims.
Musk's alleged past as an undocumented migrant in America is a sharp contrast to his Trump-approved rhetoric against undocumented immigrants.
Musk has committed $75 million through his super PAC to help Republican presidential nominee Donald Trump win the election on November 5. He's even run a $1 million giveaway to people who signer of his petition that supports the First Amendment.