Washington (CNN) President Donald Trump was bullish Thursday as another round of trade talks between the US and China concluded, saying a sweeping agreement was possible that includes his demands for Beijing to change its economic policies.

Still, Trump said he was prepared to enact new sanctions, and increase existing ones, if a deal isn't struck. And he suggested a handshake deal instead of a firmer agreement could extend negotiations beyond the month's end, though later the White House insisted March 1 was a "hard deadline."

Asked in the Oval Office, where he was meeting with China's top negotiator, whether a deal was possible, Trump said he wasn't sure.

"We have to get this put on paper at some point if we agree," the President said, adding that on some points, "we don't agree to yet, but I think we will agree."

He said the teams had made "tremendous progress" on a variety of sticking points, including technology transfers and intellectual property theft.

Still, he said those steps alone wouldn't suffice.

"That doesn't mean we're going to have a deal," he said.

In the Oval Office, Trump ordered a letter read aloud from Chinese President Xi Jinping in which the leader expressed a hope both sides would meet halfway in their trade talks.

Xi said in the letter that he cherished his working and personal relationship with Trump, sending Lunar New Year greetings to the Trump family and his wishes for a "happy and prosperous new year."

The remarks came as trade talks entered their second day in Washington. US officials said the discussions between the US and China are progressing -- and that negotiators are eyeing a mini-deal that would allow Trump to claim a victory and avert his threatened tariff increases.

Earlier Thursday, the President tweeted that the trade talks were progressing well but said a final agreement would come only after he meets again with his Chinese counterpart.

"No final deal will be made until my friend President Xi, and I, meet in the near future to discuss and agree on some of the long standing and more difficult points," Trump wrote.

Trump added on Twitter that "China's representatives and I are trying to do a complete deal, leaving NOTHING unresolved on the table."

Trump insisted in remarks from the Oval Office that he will accept only a comprehensive agreement, and suggested it may take longer than a month to finalize.

"This is going to be a very big deal or it's going to be a deal that we'll just postpone for a little," he said in the Oval Office, where he was signing an executive order meant to benefit US manufacturing.

"I think we can do it by March 1," Trump added. "Can we get it down on paper by March 1? I don't know."

In a White House statement, however, the March 1 deadline was reinforced.

"United States tariffs will increase unless the United States and China reach a satisfactory outcome by March 1, 2019," the statement read. "The United States looks forward to further talks with China on these vital topics."

The President is facing a cascade of self-imposed deadlines over the coming month on major agenda items, starting with federal budget negotiations before the next funding lapse on February 15.

Trump has made resetting the US relationship with China a centerpiece of his presidency, pulling out of a planned multilateral trade deal drawn up by the Obama administration and launching a trade war last year that has contributed to an economic slowdown in China -- and jitters in the US.

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At a December meeting with Xi in Argentina , Trump called for a 90-day negotiation, and agreed to delay a radical hike in tariffs on billions in Chinese goods originally slated to take effect on January 1.

Negotiations proceeded despite the partial federal government shutdown, with American negotiators flying to Beijing in early January.

In a statement posted to Chinese state-owned Xinhua news agency Tuesday, Beijing's negotiators said they had agreed to "vigorously increase imports of US agricultural products, energy products, industrial goods and service products."

The Chinese statement said that both sides had agreed to a timetable and roadmap for future talks.

Chinese Vice Premier Liu He, the top negotiator for Xi, has been in Washington this week meeting with top Trump aides, including US Trade Representative Robert Lighthizer, Treasury Secretary Steven Mnuchin and Commerce Secretary Wilbur Ross.

at the end of February, perhaps while the President is in Asia One US official said the US and China are working to set up a meeting between Xi and Trumpat the end of February, perhaps while the President is in Asia meeting with North Korean leader Kim Jong Un . Trump said a date and location for that meeting -- his second with the North Korean dictator -- would be announced early next week.

With only a month to go, the large gaps between the two sides on intellectual property and enforcement mechanisms could signal a smaller agreement is possible.

US officials told CNN that a smaller agreement, which avoids new tariffs but does not resolve every trade dispute, is a possible outcome, putting off for now a broad deal that includes major reforms to the Chinese economy.

But Trump on Thursday seemed reluctant to sign off on anything short of a major agreement.

"I want to do real things, like the deal with China," he told reporters. "I want it to be a real deal. I could do a deal with China where people would say, 'Isn't that wonderful?' It's not wonderful, I have to do the real deal. We have to open up China."

Those briefed by US negotiators said on a call with reporters that some progress had been made on the market access issues and IP enforcement, but not on stickier points tied to digital trade, subsidies and forced technology.

"The administration raised those issues this week, but China did not make an offer," said Myron Brilliant, executive vice president and head of international affairs at the US Chamber of Commerce.

At this point, there is no settled negotiation framework coming out of this week's talks in Washington. There will need to be some document in place before the two presidents meet. That means there are still gaps between the two sides.

"Before the presidents meet, we need a document with the key issues areas and we're not there yet," said Brilliant. "We don't have two sides working off a joint document, and that would suggest that we still have gaps."

Trump said US negotiators would travel to China in February to continue the talks.

Trump has demanded China make the concessions in exchange for dropping the tariffs he imposed last year, sparking a wave of retaliatory measures from Beijing.

On Thursday morning, he tweeted that China must open its market to US financial services, manufacturing, agriculture and other sectors before he can agree to any deal.

"Without this a deal would be unacceptable!" he wrote.