"Good for Hallie Biden," says an August 31, 2022 tweet with a screenshot of the account.
The image appears to show Hallie Biden saying she is "coming out as a Donald Trump supporting Republican" and that she has information about the Biden family "that will shock the public."
Similar messages have circulated on Instagram, with one user writing: "At least there is one smart Biden."
TikTok and Facebook users have also shared screenshots of posts from the purported account -- some of which include unsubstantiated claims about sexual abuse and the legitimacy of the 2020 US presidential election. Others mention Joe Biden's other son Hunter, who dated Hallie after Beau's death from brain cancer in 2015.
But a spokesperson for the Beau Biden Foundation, whose board Hallie Biden chairs, said the page shown online does not belong to her.
"Mrs. Hallie Biden does not have a Twitter account," the spokesperson said in an email to AFP. "Any account bearing her name is fraudulent."
The Twitter account @HallieBiden was active on August 29, 2022, but it was later suspended for violating the platform's rules -- which prohibit impersonation. One of the posts solicited contributions to a self-described "proud Trump-supporting libertarian" and "conservative author."
The account was created in August 2022 and garnered at least 18,800 followers before being suspended. Twitter had not verified the page.
AFP reached out to Twitter for additional comment.