WASHINGTON (Reuters) - U.S. President Donald Trump on Tuesday warned China against waiting out his first term to finalize any trade deal, saying if he wins re-election in the November 2020 U.S. presidential contest, the outcome will be worse for China.

As a new round of U.S.-China trade negotiations got underway in Shanghai, Trump said on Twitter: “The problem with them waiting ... is that if & when I win, the deal that they get will be much tougher than what we are negotiating now ... or no deal at all.”

Trump said China appeared to be backing off on a pledge to buy U.S. agricultural products, which U.S. officials have said could be a goodwill gesture and part of any final pact here.

“China ... was supposed to start buying our agricultural product now - no signs that they are doing so. That is the problem with China, they just don’t come through,” Trump wrote in a series of tweets.

U.S. and Chinese officials restarted negotiations after talks stalled in May, in a bid to end the year-long trade war marked by tit-for-tat tariffs, but must still resolve deep differences, keeping expectations for this week’s two-day meeting low.

The talks were expected to center on “goodwill” gestures such as Chinese commitments to purchase U.S. agricultural commodities and steps by the United States to ease some sanctions on Chinese telecoms equipment giant Huawei Technologies Co Ltd, a person familiar with the discussions told Reuters.

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HUAWEI LICENSE DECISIONS

In Sao Paulo, U.S. Commerce Secretary Wilbur Ross said decisions on license applications by U.S. firms to resume some sales to Huawei could come as early as next week.

The Commerce Department put Huawei on a national security blacklist in May, effectively banning U.S. firms from selling to Huawei, a move that enraged Chinese officials.

Trump had agreed last month to allow some sales to Huawei in a meeting with Chinese President Xi Jinping, but so far, U.S. semiconductor and software makers are still mostly in the dark about the administration’s plans.

The trade war between the world’s two largest economies has rattled global financial markets that have also been pressured by this week’s U.S. Federal Reserve policy meeting and renewed concerns over Britain’s exit from the European Union.

Speaking later to reporters at the White House, Trump said the trade talks were going well with China, but added the United States would “either make a great deal or no deal at all.”

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SHANGHAI DINNER

The U.S. negotiating team arrived for talks in Shanghai Tuesday afternoon but there was no sighting of U.S. Trade Representative Robert Lighthizer or U.S. Treasury Secretary Steven Mnuchin.

The U.S. and Chinese delegations later appeared to have reached Shanghai’s historic riverfront Fairmont Peace Hotel where sources say the U.S. delegations are having dinner, but both teams avoided the media and did not make public comments.

Trump has targeted China as part of his “America First” campaign that helped him win the White House in 2016, demanding sweeping changes to the way China does business with the rest of the world. U.S. negotiators have demanded new protections for American intellectual property, an end to forced technology transfers, curbs to Chinese industrial subsidies, broader access Chinese markets and increased Chinese purchases of U.S. goods to help balance a massive trade gap.

Trump has staked his re-election bid in part on the strength of the U.S. economy and revamping U.S. trade relations with China, Europe, Japan, Mexico and Canada.

On Tuesday, Trump also reiterated that Beijing might stall talks in hopes of inking a laxer deal with “somebody like Elizabeth Warren or Sleepy Joe Biden,” singling out two Democratic presidential front-runners, before reversing course.

“China is dying to make a deal with me. But whether or not I do it, is up to me. It’s not up to them,” he said. “China is willing to give up a lot. But that doesn’t mean I’m willing to accept it.”