WASHINGTON (Reuters) - U.S. Trade Representative Robert Lighthizer will lead negotiations with China over tariffs, market access and structural changes to intellectual property practices over the next 90 days, the White House has confirmed, potentially signaling a harder U.S. line.

U.S. Trade Representative Robert Lighthizer testifies before a Senate Finance Committee hearing on "President Trump's 2018 Trade Policy Agenda" on Capitol Hill in Washington, U.S., March 22, 2018. REUTERS/Kevin Lamarque

On Saturday, U.S. President Donald Trump and Chinese President Xi Jinping declared a trade truce, agreeing to hold off on new tariffs following months of escalating tension. The two sides also agreed to negotiate over the next 90 days.

Lighthizer leading the talks marks a shift from the administration’s previous approach to China trade talks that had been largely led by U.S. Treasury Secretary Steven Mnuchin. Lighthizer, an experienced trade negotiator and having just completed a new agreement with Canada and Mexico, is one of the administration’s most vocal China critics.

“Robert Lighthizer, the ambassador, USTR, is in charge of these negotiations,” White House trade adviser Peter Navarro told National Public Radio. “He’s the toughest negotiator we’ve ever had at the USTR and he’s going to go chapter and verse and get tariffs down, non-tariff barriers down and end all these structural practices that prevent market access.”

A White House official also confirmed the decision to have Lighthizer lead the negotiations.

Mnuchin had said the negotiations with China would be led by Trump, with an “inclusive team” of administration officials, including himself and other cabinet officials.

Mnuchin led some past rounds of talks due to his relationship as the counterpart to Chinese Vice Premier Liu He, the top economic adviser to Chinese President Xi Jinping. U.S. Commerce Secretary Wilbur Ross also led a failed round of talks in Beijing in June, while mid-level Treasury officials hosted a round of discussions in August.

The White House said on Saturday that the talks would cover structural changes in China on forced technology transfer, intellectual property protection, non-tariff barriers, cyber intrusions and cyber theft, services and agriculture.

Most of these issues were identified in USTR’s “Section 301” investigation of China’s intellectual property practices, which formed the basis of the U.S. tariffs imposed on Chinese goods.

Lighthizer said last week that China had failed to alter the “unfair, unreasonable” practices at the heart of the trade dispute.