Members of the House Select Committee on China have directed Apple and Google to prepare for TikTok’s potential removal from U.S. app stores next month.

Representatives John Moolenaar, R-Mich., and Raja Krishnamoorthi, D-Ill., sent letters on December 13 to Apple CEO Tim Cook and Alphabet CEO Sundar Pichai outlining their obligations under the law. The directive follows the U.S. Court of Appeals in Washington, D.C.’s decision to uphold legislation mandating ByteDance to divest TikTok by January 19.

If ByteDance fails to sell TikTok by the deadline, the law requires Apple and Google to cease supporting the app on their U.S. platforms. The Appeals Court rejected TikTok’s request for a temporary stay of the law’s implementation.

The lawmakers emphasized that TikTok has had 233 days since President Biden signed the original legislation in April to address national security concerns. TikTok’s legal challenge, which argued that the law violates the First Amendment rights of its 170 million U.S. users, was dismissed by a three-judge panel.

The U.S. Justice Department states that if the ban takes effect on Jan. 19, it would “not directly prohibit the continued use of TikTok” by Apple or Google users who have already downloaded TikTok. However, it conceded the prohibitions on providing support “will eventually be to render the application unworkable.”

TikTok projects that a one-month suspension would result in U.S. small businesses and content creators losing over $1 billion in sales and earnings.

The law specifically prohibits app store operators from providing services to “distribute, maintain, or update such foreign adversary controlled application” within U.S. borders if ByteDance fails to divest TikTok by the deadline.

The transition of power in Washington adds another layer of uncertainty to the situation. President-elect Donald Trump, who takes office on January 20, expressed support for TikTok during his election campaign this year.