U.S. officials have said TikTok under its Chinese parent poses a national risk because of the personal data it handles. Trump said on Friday he was planning to ban TikTok in the United States after dismissing the idea of a sale to Microsoft.

But following a discussion between Trump and Microsoft CEO Satya Nadella, the Redwood, Washington-based company said in a statement on Sunday that it would continue negotiations to acquire TikTok from ByteDance, and that it aimed to reach a deal by Sept. 15.

It was not immediately clear what changed Trump’s mind. Banning TikTok would alienate many of its young users ahead of the U.S. presidential election in November, and would likely trigger a wave of legal challenges. Several prominent Republican lawmakers put out statements in the last two days urging Trump to back a sale of TikTok to Microsoft.

“A win-win in the making,” Republican Senator Lindsey Graham tweeted in response to Trump’s new stance on Sunday.

The negotiations between ByteDance and Microsoft will be overseen by the Committee on Foreign Investment in the United States (CFIUS), a U.S. government panel that has the right to block any agreement, according to the sources, who requested anonymity ahead of a White House announcement. Microsoft cautioned in its statement that there is no certainty a deal will be reached.