WASHINGTON (Reuters) -U.S. President Donald Trump will extend a June 19 deadline for China-based ByteDance to divest the U.S. assets of short video app TikTok for 90 days despite a law that mandated a sale or shutdown absent significant progress, the White House said on Tuesday.

Trump had already twice granted a reprieve from enforcement of a congressionally mandated ban on TikTok that was supposed to take effect in January. "President Trump will sign an additional executive order this week to keep TikTok up and running," White House press secretary Karoline Leavitt said Tuesday.

That would extend the deadline to mid-September.

"President Trump does not want TikTok to go dark," she added, saying the administration will spend the next three months making sure the sale closes so that Americans can keep using TikTok with the assurance that their data is safe and secure.

Trump said in May he would extend the June 19 deadline after the app helped him with young voters in the 2024 election.

Earlier on Tuesday, he had told reporters on Air Force One he expected to again extend the deadline.

"Probably, yeah," Trump said when asked about extending the deadline. "Probably have to get China approval but I think we'll get it. I think President Xi will ultimately approve it."

The law required TikTok to stop operating by January 19 unless ByteDance had completed divesting the app's U.S. assets or demonstrated significant progress toward a sale.

Trump began his second term as president on January 20 and opted not to enforce it. He first extended the deadline to early April, and then again last month to June 19.

In March, Trump said he would be willing to reduce tariffs on China to get a deal done with TikTok's Chinese parent ByteDance to sell the short video app used by 170 million Americans.

A deal had been in the works this spring that would spin off TikTok's U.S. operations into a new U.S.-based firm and majority-owned and operated by U.S. investors, but it was put on hold after China indicated it would not approve it following Trump's announcements of steep tariffs on Chinese goods.

Democratic senators argue that Trump has no legal authority to extend the deadline, and suggest that the deal under consideration would not meet legal requirements.