The Supreme Court seemed likely Friday to uphold the law that could ban TikTok, with most of the justices appearing to take seriously the national security risks posed by the wildly popular app whose parent company is based in China.

U.S. government says Chinese authorities could force the company to hand over sensitive data on its massive American user base or influence the spread of information on the platform through its proprietary algorithm.

TikTok says those concerns are overblown and the law should be struck down because it violates the First Amendment.

The law would ban TikTok in the U.S., unless it’s sold away from its Chinese parent company.

The measure is set to take effect Jan. 19, the day before a new term begins for President-elect Donald Trump, who has 14.7 million followers on the platform. The Republican says he wants to “save TikTok.”

Congress passed the measure with bipartisan support, and President Joe Biden, a Democrat, signed it into law in April.

TikTok’s lawyers challenged the law in court, joined by users and content creators who say a ban would upend their livelihoods. TikTok says the national security concerns are based on inaccurate and hypothetical information.

But a unanimous appeals court panel made up of judges appointed by both Republican and Democratic presidents has upheld the law. The court normally takes months to decide cases, but the justices could take action on this case within days, lightning-fast movement by court standards.

TikTok lawyers want the justices to step in before the law takes effect on Jan. 19, saying even a monthlong shutdown would cause the app to lose about one-third of its daily American users and significant advertising revenue.

But during oral arguments, conservative and liberal justices seemed more receptive to the government’s arguments that the danger was real and the law’s biggest effect is on the parent company ByteDance, a foreign corporation without First Amendment guarantees.

The justices, most notably Neil Gorsuch, still had tough questions from the government about how the law might affect free speech of the people who post on the app, and whether the government should be in the business of preventing the spread of misinformation.