WASHINGTON (AP) --

The Supreme Court 's decision could come Friday in the case about whether TikTok must shut down in a few days under a federal law that seeks to force its sale by the Chinese company that owns the social media platform used by 170 million people in the U.S.

The justices are weighing a free speech challenge to the law, which takes effect Sunday, against the national security concerns that prompted its enactment with broad bipartisan support last year. A lawyer for TikTok and ByteDance, its Chinese owner, told the court last week that TikTok will "go dark" on Sunday unless the justices grant it a temporary reprieve or strike down the law.

During courtroom arguments, most of the justices seemed likely to uphold the law.

Alongside the ongoing court case, a potential lifeline for TikTok has emerged. President-elect Donald Trump, who once supported banning the app, is exploring options to "preserve" TikTok, his incoming national security adviser, Florida Rep. Mike Waltz, said in a televised interview on Wednesday.

It's not clear what authority Trump has to intervene, although he could direct the Justice Department not to enforce the law, which threatens sanctions against the technology companies that make the app available and host it.

The Supreme Court indicated Thursday that the justices will issue at least one decision Friday, adhering to its custom of not saying which one. But it also departed from its usual practice in some respects, heightening the expectation that it's the TikTok case that will be handed down.

Except for when the end of the term nears in late June, the court almost always issues decisions on days when the justices are scheduled to take the bench. The next scheduled court day is Tuesday.

And apart from during the coronavirus pandemic, when the court was closed, the justices almost always read summaries of their opinions in the courtroom. They won't be there Friday.

Any opinions will post on the court's website beginning just after 10 a.m. EST Friday.