U.S. Trade Representative Robert Lighthizer speaks during a meeting on trade held by U.S. President Donald Trump with governors and members of Congress at the White House on April 12, 2018 in Washington, DC.

United States Trade Representative Robert Lighthizer saw no progress on key issues in last week's talks aimed at settling the ongoing trade dispute between the United States and China, according to Sen. Chuck Grassley.

The Iowa Republican said Lighthizer believes negotiators made little headway in resolving structural issues at the heart of the dispute.

"He said that there hasn't been any progress made on structural changes that need to be made," Grassley told reporters on a conference call. "Let's say that would include intellectual property, stealing trade secrets, putting pressure on corporations to share information with the Chinese government and industries."

"So structure-wise not much progress, but the Chinese are coming over here in a couple weeks and there will be more negotiations," he said.

Grassley believes there is a chance for progress, based on his view that China's economy is suffering. He said Lighthizer commented "positively" on China resuming purchases of American goods like soybeans.

The Dow Jones Industrial Average gave up a 100-point gain after Grassley's comments.

Washington and Beijing reached a truce last month that prevented the two countries from increasing tariffs on hundreds of billions of dollars worth of one another's goods after Jan. 1. The agreement lasts for 90 days, after which a 10 percent tariff on $200 billion in Chinese imports will increase to 25 percent if no deal is reached.

U.S. negotiators traveled to Beijing last week to lay the groundwork for a long-term deal. The talks, originally scheduled for two days, stretched into a third day, a development that was generally seen as a positive sign of progress.

Lighthizer's view of the talks is another sign that administration officials are taking a more measured view of negotiations than President Donald Trump. After reaching the truce, Trump called it "one of the largest deals ever made," and has more recently said trade talks are going "very well!"

@realDonaldTrump: Talks with China are going very well!