It isn’t clear what the valuation of TikTok’s U.S. operations would be, but estimates run into the tens of billions of dollars, which raises questions about how Twitter would finance any deal. Twitter’s market capitalization is about $29 billion and Microsoft’s is more than $1.6 trillion.

Because it is much smaller, Twitter has reasoned that it would be unlikely to face the same level of antitrust scrutiny as Microsoft or other potential bidders, said people familiar with the discussions.

Twitter would almost certainly need help from other investors if it does buy TikTok. The company has far less financial firepower than other major tech players, though it does have high-powered investors such as private-equity firm Silver Lake. Twitter started making a consistent profit in the past couple of years, but reported a $1.23 billion loss in the latest quarter. Twitter reported $7.8 billion in cash and short-term investments as of June, compared with more than $136 billion for Microsoft.