President Donald Trump tweeted Wednesday that a new China trade deal "will probably have to use a different structure" than the one announced just four days ago.

Trump appears to be cooling off on the trade deal despite praising the agreement Monday.

The reversal comes after heavy criticism of the deal by Democrats, Republicans, and economists.

Experts say Trump's change in tune could also be linked to the planned summit with North Korean leader Kim Jong Un.

Just four days after celebrating a preliminary trade agreement with China, President Donald Trump is signaling a potential reverse in course.

In a tweet Wednesday morning, Trump suggested a final deal with China would need to be substantially altered from the initial agreement.

"Our Trade Deal with China is moving along nicely, but in the end we will probably have to use a different structure in that this will be too hard to get done and to verify results after completion," Trump said.

The comments came the day after Trump expressed doubt about the recent trade negotiations during a back-and-forth with reporters in the Oval Office. When asked if he was pleased with the trade talks so far he replied, "No, not really."

"No, I'm not satisfied, but we'll see what happens," Trump said about the negotiations later. "We have a long way to go. But I wanted to go fairly quickly."

But Trump had earlier praised the deal. On Monday, Trump tweeted that it would be a boon for America's farmers.

"China has agreed to buy massive amounts of ADDITIONAL Farm/Agricultural Products - would be one of the best things to happen to our farmers in many years!" Trump said.

The deal, announced Saturday, would indefinitely delay Trump's tariffs on $150 billion worth of Chinese goods while China would increase imports of US agricultural and energy goods.

Trump expressed disappointment with President Xi Jinping's recent meeting with North Korean leader Kim Jong Un immediately after discussing the trade negotiations.

Analysts have said the upcoming summit in Singapore could have major ramifications for the China trade talks. If they fall apart, Trump may be inclined to take his frustration out on China.

"Should Singapore falter, we would expect the America First trade hawks to retake the commanding heights inside 1600 Pennsylvania Avenue with the 301 tariffs loaded for Chinese bear," Chris Krueger, a strategist at Cowen Washington Research Group, wrote in a note to clients. "The argument to Trump being you never should have gone against your instincts and let the Globalists lull you into a bad deal with China that got us nowhere with Kim Jong-un."

Trump on Tuesday cast significant doubt on the summit's status, suggesting it could be delayed and musing about whether it would even happen at all.

US President Donald Trump and Chinese President Xi Jinping Andrew Harnik/AP Images

Trump's reversal comes after heavy bipartisan criticism

Trump's about-face also comes after days of heavy criticism from lawmakers and economists on both sides of the political spectrum.

Democrats and Republicans in Congress alike took issue with the agreement. Democratic Sen. Ron Wyden said Trump was "simply getting rolled on trade with China," while GOP Sen. Marco Rubio complained that China is "out-negotiating the administration & winning the trade talks right now."

Outside of Capitol Hill, trade policy specialists also criticized the agreement.

Edward Alden, a senior fellow at the Council on Foreign Relations who specializes in economic issues, blasted the the limited scope and negotiating tactics used to reach the deal.

"If nothing further is done, the US-China trade deal reached this month will be remembered, to quote a phrase coined by the current president of the United States, as 'the single worst trade deal' ever negotiated," Alden wrote in a reference to Trump's term for the North American Free Trade Agreement (NAFTA).

Even more Trump-friendly trade experts took issue. Derek Scissors, a resident scholar at the American Enterprise Institute and one-time adviser to Trump on trade issues, said Trump had gone back on campaign promises.

"Candidate Donald Trump in 2016 accused China of economic rape. President Trump this year said trade wars are easy to win," Scissors wrote. "Both claims are partly true. China has seriously harmed the American economy. And, while we haven’t actually had a trade war with China, they may be about to win anyway. Easily."