By David Shepardson and Michael Martina

WASHINGTON (Reuters) -A bipartisan group of U.S. lawmakers is introducing legislation on Tuesday that would give China’s ByteDance about six months to divest popular short video app TikTok or face a U.S. ban.

Representative Mike Gallagher, the Republican chair of the House of Representatives’ select China committee and Representative Raja Krishnamoorthi, the top Democrat, are introducing legislation along with more than a dozen other lawmakers to address national security concerns posed by Chinese ownership of the app, aides said.

“Applications like TikTok that are controlled by foreign adversaries pose an unacceptable risk to U.S. national security,” the lawmakers said in a fact sheet.

TikTok did not immediately comment.

The bill would give ByteDance 165 days to divest TikTok, which is used by more than 170 million Americans, or it would be unlawful for app stores operated by Apple, Google and others to offer TikTok or to provide web hosting services to ByteDance-controlled applications. The bill would not authorize any enforcement against individual users of an affected app.

Senate legislation to ban the popular app stalled in Congress last year in the face of heavy lobbying by TikTok. The bill marks the first significant legislative movement toward banning or forcing ByteDance to divest the app in nearly a year.

The bill, which would required companion legislation in the Senate, is expected to be taken up at an Energy and Commerce Committee hearing Thursday for a potential vote and could pose a significant threat to ByteDance’s ownership of TikTok.

Still the app is very popular and getting legislation approved in an election year may be difficult. Last month, Democratic President Joe Biden’s reelection campaign joined TikTok.

The bill would give the president new powers to designate apps of concern posing national security risks and face bans or restrictions absent divestiture. It would apply to apps with “over one million annual active users, and is under the control of a foreign adversary entity.”

Concerns about Chinese-owned TikTok last year sparked efforts in Congress to boost powers to address the popular short video sharing app or potentially ban it.

The White House, which did not immediately comment on the new bill, backed legislation sponsored by Senator Mark Warner and more than two dozen other senators last year to give the administration new powers to ban TikTok and other foreign-based technologies if they pose national security threats. That bill has never been voted on.

The U.S. Treasury-led Committee on Foreign Investment in the United States (CFIUS) in March 2023 demanded that TikTok’s Chinese owners sell their shares, or face the possibility of the app being banned, Reuters and other news outlets reported, but the administration has taken no action.

The new bill is aimed at bolstering the legal authority to address TikTok concerns. Biden’s predecessor, Republican Donald Trump, tried to ban TikTok in 2020 but was blocked by U.S. courts.

Other Chinese non-social media apps, such as those run by retailers Shein and Temu, would not be covered by the bill, aides said.

(Reporting by David Shepardson; Editing by Chizu Nomiyama and Jonathan Oatis)