A group of Republican senators led by Sen. Tom Cotton (R-Ark.) on Tuesday raised concerns that popular social media app TikTok could be used by the Chinese Communist Party (CCP) to spread disinformation around U.S. elections.

The GOP lawmakers wrote to the FBI, the Department of Homeland Security and the Office of the Director of National Intelligence raising concerns that the app could be used by China to interfere in American elections.

TikTok is owned by Chinese company ByteDance, which is subject to Chinese intelligence laws, an issue that has increasingly led to questions over the security and privacy of American data stored by the app. The company has taken steps to separate itself from China, including hiring an American CEO and moving the storage of American data to the U.S.

But the senators still warned that the CCP could use the app for its purposes, noting that TikTok temporarily locked a teen’s account last year after the individual posted a video critical of the CCP’s treatment of Uighur Muslims.

They asked that the agencies respond to questions around whether TikTok could be subject to sanctions if disinformation efforts are found on its platform, and whether the app could serve as a tool for the CCP to interfere in U.S. elections.

Biden campaign also takes action: Staffers on the presidential campaign of former Vice President Joe Biden were told Tuesday to either delete TikTok from their phones and to not download the app in the future.