The agreement is at the top of the agenda alongside trade for the leaders' first known call in three months, expected on Friday morning, Washington time, US officials said.
China has not confirmed plans for the call.
Trump and Xi's effort to steady relations comes as the two governments have been discussing a potential in-person summit between Xi and Trump during the Asia-Pacific Economic Co-operation summit in South Korea on October 30-November 1, Reuters has reported.
Beijing's sign-off is one of the hurdles Trump needed to clear to keep TikTok open.
Congress had ordered the app shut down for US users by January 2025 if its US assets were not sold by Chinese owner ByteDance.
Trump has declined to enforce the law while his administration looks for a new owner, but also because he worries a ban on the app would anger TikTok's huge user base and disrupt political communications.
"I like TikTok; it helped get me elected," Trump said during a media conference on Thursday.
"TikTok has tremendous value. The United States has that value in its hand because we're the ones that have to approve it."
Key questions about the deal remain. It's not clear the precise ownership structure of the company, how much control China will retain or whether Congress will approve.
The deal would transfer TikTok's US assets to US owners from ByteDance, Reuters has reported, while sources familiar with the deal said US TikTok would still make use of ByteDance's algorithm.
That arrangement worries lawmakers concerned that Beijing could spy on Americans or conduct influence operations through the app.
China has said there is no evidence of a national security threat posed by the app.
Trump has positioned his foreign policy approach as one of peace-seeking and deal-making, but relations remain icy between the world's two biggest economies.
"We're pretty close to a deal," Trump said on Thursday, in an apparent reference to larger trade talks.
"We may do an extension with China, but it's an extension based on the same terms that we have right now, which are pretty good terms."
Other key issues include competition between both sides on semiconductors and other advanced technologies.
The US wants more Chinese purchases of US-harvested soybeans and Boeing aeroplanes.
The US is also demanding that China crack down on the export of fentanyl-related chemicals, a major cause of US overdose deaths.
Beijing has accused Washington of distorting the issue.
Recent data point to slowing economies in both China and the United States.
Since retaking office in January, Trump sharply hiked tariffs across the board and singled out China's export-oriented economy with especially punitive rates.
That prompted China to respond in kind. Tariff rates on both sides of the Pacific rose to triple-digit percentages in April.
A succession of limited agreements since May paused the tit-for-tat tariff war between the countries.
