Former President Donald Trump recently said he opposed a federal ban on TikTok — which could take effect as early as January — but it’s unclear whether he could preempt the ban already passed by President Joe Biden, who is embroiled in legal challenges, from taking effect.

Biden signed the TikTok ban in April, which requires ByteDance — TikTok’s China-based parent company — to sell the platform by January or face being banned from U.S. app stores.

TikTok and ByteDance almost immediately challenged the law in court, filing a lawsuit claiming the law was targeted, unconstitutional, and violated the First Amendment, and that it was not “technologically, commercially, or legally feasible” to waive the deadline.

Donald Trump previously signed an executive order in 2020 that would have made the app illegal, but that was blocked by a court.

After meeting with Jeff Yass, a major Republican donor who had a major financial interest in the app in March, Trump rescinded his decision. He later joined the platform and vowed to “never stop TikTok.”

Trump also said the ban would only help Mark Zuckerberg and Facebook, whom he considers “the enemy of the people,” and later campaigned on his support for TikTok, saying in September: “To anyone who wants to save TikTok in America, vote for Trump.”