Biden the President Wants to Curb TikTok. Biden the Candidate Embraces Its Stars.

The White House is so concerned about the security risks of TikTok that federal workers are not allowed to use the app on their government phones. Top Biden administration officials have even helped craft legislation that could ban TikTok in the United States.

But those concerns were pushed aside on Thursday, the night of President Biden’s State of the Union address, when dozens of social media influencers — many of them TikTok stars — were invited to the White House for a watch party.

The crowd took selfies in the State Dining Room, drank bubbly with the first lady and waved to Mr. Biden from the White House balcony as he left to deliver his speech to Congress.

“Don’t jump, I need you!” Mr. Biden shouted to the young influencers filming from above, in a scene that was captured — naturally — in a TikTok video, which was beamed out to hundreds of thousands of people.

Thursday’s party at the White House was an example of Mr. Biden’s political concerns colliding head-on with his national security concerns. Despite growing fears that ByteDance, the Chinese parent company of TikTok, could infringe on the personal data of Americans or manipulate what they see, the president’s campaign is relying on the app to energize a frustrated bloc of young voters ahead of the 2024 election.

“From a national security perspective, the campaign joining TikTok was definitely not a good look — it was condoning the use of a platform that the administration and everyone in D.C. recognizes is a national problem,” said Lindsay Gorman, head of technology and geopolitics at the German Marshall Fund and a former tech adviser for the Biden administration.

TikTok is the second-most popular platform among U.S. teenagers behind YouTube, making it an alluring political tool. But concerns about the app’s structure have been growing, and a House committee advanced a bill this week that would keep TikTok out of U.S. app stores unless the platform broke from ByteDance.

Former President Donald J. Trump attacked the Biden administration for potentially banning TikTok, saying that would only empower Meta, the parent company of Facebook.Credit...Ore Huiying for The New York Times

When members of Congress talk about TikTok they tend to focus on the privacy concerns, and whether data about users is stored in China or accessible to Chinese officials who could demand the company turn over the information.

But national security officials have a deeper concern: The algorithms that guide what users see are now almost entirely designed in China. The key is to prevent Chinese engineers, perhaps under the influence of the state, from using the code in ways that could censor, or manipulate, what American users see. TikTok has pushed back on such concerns, saying that its opponents haven’t produced evidence to back those fears.

That is particularly important, officials say, as election season nears. If Chinese officials sought to influence the election, the app might provide a subtle way to do so. But even the legislation now wending through Congress might not affect that: It would not go into effect for more than five months after a bill is signed. At most, that would be just a month or so before Election Day.

The White House has been supportive of constraints.

Mr. Biden’s National Security Council called the bill in the House “an important and welcome step” and the White House press secretary, Karine Jean-Pierre, said it should move quickly to the president’s desk for his signature. While the legislation’s road in the Senate is unclear, Mr. Biden asserted on Friday that he approved of the package.

“If they pass it, I’ll sign it,” Mr. Biden said.

ByteDance has spent Mr. Biden’s tenure promoting a plan to eliminate security concerns about TikTok by storing its American user data on Oracle servers in the United States. That plan was at the heart of a 2022 draft agreement between ByteDance and administration negotiators. But senior administration officials had concerns at the time that the proposed agreement didn’t go far enough to address their concerns.