WASHINGTON - Two Democratic lawmakers on Monday urged Congress and President Joe Biden to extend a Jan. 19 deadline for China-based ByteDance to sell the U.S. assets of TikTok or face a U.S. ban.

The Supreme Court held arguments Friday on Tiktok and ByteDance's challenge to the law. A lawyer for the companies, Noel Francisco, said it would be impossible to complete a sale by next week's deadline.

He said if banned, the the short video app used by 170 million Americans would quickly go dark and "essentially the platform shuts down."

Biden could extend the deadline by 90 days if he certifies ByteDance is making substantial progress toward a divestiture but it is unlikely ByteDance could meet that standard.

Senator Edward Markey said he planned to introduce legislation to delay the deadline by which ByteDance must sell TikTok or face a ban by an additional 270 days.

"A ban would dismantle a one-of-a-kind informational and cultural ecosystem, silencing millions in the process," Markey said Monday.

"A TikTok ban would impose serious consequences on millions of Americans who depend on the app for social connections and their economic livelihood. We cannot allow that to happen."

President-elect Donald Trump has asked the court to delay implementation of the law, arguing he should have time after taking office on Jan. 20 to pursue a "political resolution" to the issue.

Representative Ro Khanna, a Democrat, on Monday urged Biden and Trump "to put a pause on this ban so 170 million Americans don't lose their free speech. Millions of Americans' livelihood will be ended if this ban takes place."

If the court does not block the law by Sunday, new downloads of TikTok on Apple or Google app stores would be banned but existing users could continue to access the app for some period. Services would degrade and eventually stop working as companies will be barred from providing support.

The White House did not immediately comment.