A US congressional committee has passed legislation that would require TikTok's China-based parent firm to sell the app within six months or risk a ban.
The legislation, presented by another House committee and supported by the White House, raises national security concerns.
TikTok claims the new regulation will harm free expression and small companies that rely on the service.
It is requesting that its users contact members of Congress and express their objections.
The social media company revealed to the BBC that it had issued a message requesting TikTok users to "call your representative now" in order to urge them to vote against the proposal.
One congressional aide informed the BBC that their office had received a multitude of calls in this regard.
According to the New York Times, several phone lines were swamped, and a handful of the callers seemed to be minors.
The bill is scheduled to be voted on by the entire House next week.
The Energy and Commerce Committee approved it overwhelmingly, 50-0, on Thursday. Before it could become law, the Senate would have to give its approval.
The committee chairperson criticized TikTok for mobilizing its followers, to which the site responded: "Why are members of Congress objecting to hearing from their constituents? With respect, isn't that their job?"
The legislation states that it will "shield the national security of the US from the risk generated by foreign adversary-controlled apps."
Lawmakers say that TikTok's owner, ByteDance, has ties to the Chinese Communist Party, which ByteDance and TikTok both deny.
This article was originally published on the BBC.