A U.S. federal appeals court on Friday left in place a mid-January deadline for a federal law requiring TikTok to be sold or banned to take effect, rejecting the company's request to halt enforcement of the law until the Supreme Court reviews its challenge.

Attorneys for TikTok and its China-based parent company, ByteDance, are expected to appeal to the Supreme Court.

It's unclear if the country's highest court will take up the case, though some legal experts have said they expect the justices to weigh in due to the types of novel questions it raises about social media, national security and the First Amendment.

TikTok is also looking for a potential lifeline from president-elect Donald Trump, who promised to "save" the short-form video platform during the presidential campaign.

Attorneys for TikTok and ByteDance had requested the injunction after a panel of three judges on the U.S. Court of Appeals for the District of Columbia Circuit sided with the U.S. government and rejected their challenge to the law.

The statute, which was signed by U.S. President Joe Biden earlier this year, requires ByteDance to sell TikTok to an approved buyer or face a ban in the U.S. due to national security concerns.

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The U.S. has said it sees TikTok as a national security risk because ByteDance could be coerced by Chinese authorities to hand over U.S. user data or manipulate content on the platform for Beijing's interests. TikTok has denied those claims and has argued that the government's case rests on hypothetical future risks instead of proven facts.

In the request filed last week, attorneys for TikTok and ByteDance asked for a "modest delay" in enforcement of the law so that the Supreme Court could review the case and the incoming Trump administration could "determine its position" on the matter.

If the law is not overturned, the two companies have said that the popular app will shut down by Jan. 19, just a day before Trump takes office again. More than 170 million American users would be affected, the companies have said.

The Justice Department had opposed TikTok's request for a pause, saying in a court filing last week that the parties had already proposed a schedule that was "designed for the precise purpose" of allowing Supreme Court review of the law before it took effect.

The appeals court issued its Dec. 6 ruling on the matter in line with that schedule, the Justice Department filing said.