TikTok cut off access to its U.S. users late Saturday, just before a national ban on the app was set to take effect, with President-elect Donald Trump unable to intervene until he takes office.

"A law banning TikTok has been enacted in the US," a message appeared for users trying to access the app. "Unfortunately, that means you can't use TikTok for now."

"We are fortunate that President Trump has indicated that he will work with us on a solution to reinstate TikTok once he takes office," the message added. "Please stay tuned!"

After months of legal battles, the U.S. Supreme Court upheld a law on Friday banning the popular video-sharing platform over national security concerns, unless its Chinese owner, ByteDance, sells it to non-Chinese buyers by Sunday.

From teenage dancers to grandmothers sharing cooking tips, TikTok has gained popularity for its ability to turn ordinary users into global celebrities when a video goes viral. It also has a fan in Trump, who credited the app with helping him connect to younger voters, contributing to his November election victory.

Following a discussion with Chinese President Xi Jinping, Trump told NBC News on Saturday that he could grant a 90-day reprieve once he assumes office.

"I think that would be, certainly, an option that we look at. The 90-day extension is something that will be most likely done, because it's appropriate," he said ahead of his inauguration on Monday. "If I decide to do that, I'll probably announce it on Monday."

The law allows a 90-day delay if the White House shows progress toward a viable deal, but TikTok owner ByteDance has refused any sale.

The administration of outgoing President Joe Biden has deferred the issue to Trump, and White House spokeswoman Karine Jean-Pierre dismissed TikTok's latest statements as a "stunt."

After the court's ruling, TikTok CEO Shou Chew thanked Trump for his "commitment to work with us to find a solution," adding that Trump "truly understands our platform."

Chew is also scheduled to attend Trump's inauguration on Monday.

The law requires Apple and Google to remove TikTok from their app stores, blocking new downloads. The companies could face penalties of up to $5,000 per user who accesses the app.

Oracle, which hosts TikTok's servers, would also be legally required to enforce the ban.

None of the companies responded to requests for comment on Saturday.

Offers for TikTok

A last-minute proposal from startup Perplexity AI on Saturday suggested a merger with TikTok's U.S. subsidiary, a source familiar with the deal told AFP. The proposal could provide a potential solution for ByteDance without requiring it to sell the app entirely.

First reported by CNBC, the plan would create a joint venture combining U.S. TikTok's assets and Perplexity AI, backed by Amazon founder Jeff Bezos.

The proposal did not include a price, but the source estimated the transaction would be valued at least $50 billion.

Former Los Angeles Dodgers owner Frank McCourt also offered to purchase TikTok's U.S. operations, saying he's "ready to work with the company and President Trump to complete a deal."

Canadian investor Kevin O'Leary, involved in that offer, told Fox News that ByteDance was offered $20 billion for TikTok's U.S. operations.

He acknowledged the legal uncertainty surrounding the case, noting that it remains unclear whether an executive order by Trump to halt the ban would override the law.

"Congress wrote this law to be virtually president-proof," warned Adam Kovacevich, CEO of the industry trade group Chamber of Progress.

Sarah Kreps, a Cornell University professor of government and law, said that "if an executive order conflicts with an existing law, the law takes precedence, and the order can be struck down by the courts."

With TikTok facing shutdown, U.S.-based rivals Instagram Reels and YouTube Shorts stand to benefit.

Meanwhile, thousands of concerned TikTok users have turned to Xiaohongshu ("Little Red Book"), a Chinese social media platform similar to Instagram. Nicknamed "Red Note" by American users, it was the most downloaded app on the U.S. Apple Store this week.