WASHINGTON (Reuters) - U.S. President Donald Trump said on Thursday that trade talks with China were going well and he would only accept a “great” deal as negotiators hammered out differences ahead of a meeting between Trump and China’s vice premier later in the day.

U.S. President Donald Trump and China's President Xi Jinping arrive for a state dinner at the Great Hall of the People in Beijing, China, November 9, 2017. REUTERS/Jonathan Ernst

China and the United States are in the middle of intense negotiations to end a months-long trade war that has rattled global markets. Washington wants sweeping changes to China’s economic and trade policies, while Beijing wants Trump to lift expensive sanctions on Chinese goods.

The White House has no plans to announce a date on Thursday for a trade summit between Trump and Chinese President Xi Jinping, senior administration officials said, though they would not rule out the possibility.

Talks are scheduled to go through Friday and possibly longer.

“If it’s not a great deal, we’re not doing it. But it’s going very well. Top officials are here. And we’re very well along on the deal. It’s a very complex deal. It’s a very big deal,” Trump told reporters.

“It’ll be a great deal for our farmers. Technology, intellectual property theft -- everything is covered. There’s not a thing that’s not covered,” he said.

Trump is slated to meet with China’s top trade negotiator, Vice Premier Liu He, at 4:30 p.m. (2030 GMT) in the Oval Office.

The Wall Street Journal and the New York Times reported that Trump was expected to announce a date for a summit at that time, but a senior administration official told Reuters that was incorrect.

“The White House is not expected to announce a date for a meeting,” the official said.

A second administration official was a bit more cautious about prospects for an announcement, saying: “It’s possible, but I think it’s unlikely.”

Hopes that the talks were moving in a positive direction have cheered financial markets in recent weeks. But U.S. stocks were mixed on Thursday as investors waited for more developments in the trade negotiations, with the Dow Jones industrial Average slightly higher, and the S&P 500 and Nasdaq Composite slightly lower. [.N]

Trump has proven unpredictable in past White House meetings with Liu, openly challenging U.S. Trade Representative Robert Lighthizer in late February over the use of the term “memorandum of understanding” in the talks.

After meetings in Beijing last week, U.S. Trade Representative Robert Lighthizer and Treasury Secretary Steven Mnuchin are holding talks in Washington with Liu and a Chinese delegation this week.

Liu, Lighthizer and Mnuchin declined to speak to reporters as the three entered USTR offices near the White House on Thursday morning.

The second Trump administration official said that progress was being made on some issues in the talks, but others remained sticking points, such as the removal of U.S. tariffs on Chinese goods and issues related to enforcement of any agreements.

The United States is seeking reforms to Chinese practices that it says results in the theft of U.S. intellectual property and the forced transfer of technology from U.S. companies to Chinese firms.

Administration officials initially envisioned a summit between Trump and Xi potentially taking place in March, but some U.S. lawmakers and lobbying groups have said recently they were told that the administration was now aiming for a deal in late April.

DEADLINES SLIP

White House economic adviser Larry Kudlow has declined to give a deadline for a deal, saying last week that the talks are “not time dependent” and could be extended for weeks or even months longer.

While some reform pledges by Beijing are largely agreed, including an agreement to avoid currency manipulation, the two sides have not yet settled on an enforcement mechanism to ensure that China keeps its pledges. Another key unresolved issue is whether and when punitive U.S. tariffs on $250 billion worth of Chinese goods would be removed.

As the talks reach their final stages, resolving these two issues will be critical in determining whether a deal can be reached, U.S. Chamber of Commerce international affairs chief Myron Brilliant told reporters on Tuesday.

“China has been very clear, publicly and privately, that they would like to see all the tariffs removed,” Brilliant said. “The (Trump) administration has been equally clear that they want to keep some of the tariffs in place as a way to have leverage over China fulfilling its obligations under whatever final package is reached.”