The relationship between President Trump and Mexican President Peña Nieto has become strained in the past week.

WASHINGTON — President-elect Donald Trump has tapped Robert Lighthizer, an attorney specializing in international trade and a former trade official under President Ronald Reagan, as his U.S. Trade Representative.

Trump said he intends to nominate Lighthizer, who must also be confirmed by the Senate, to the post of what has traditionally been the top trade chief.

Lighthizer played a key role in developing trade policy in the Reagan administration and negotiated two dozen bilateral international agreements ranging from steel to grain that were “uniformly tough and frequently resulted in significant reductions in the shipment of unfairly traded imports into the United States,” according to Trump’s transition team.

“Ambassador Lighthizer is going to do an outstanding job representing the United States as we fight for good trade deals that put the American worker first,” Trump said. “He has extensive experience striking agreements that protect some of the most important sectors of our economy, and has repeatedly fought in the private sector to prevent bad deals from hurting Americans. He will do an amazing job helping turn around the failed trade policies which have robbed so many Americans of prosperity.”

Lighthizer said: “I am fully committed to President-elect Trump’s mission to level the playing field for American workers and forge better trade policies which will benefit all Americans.”

While the role of USTR will be that of a principal negotiator on trade deals, according to Trump’s chief spokesman, the president-elect also plans to rely on a wider circle of advisers to craft his overall trade agenda and policy, according to Sean Spicer, incoming White House press secretary.

Lighthizer will work closely with Commerce Secretary-designate Wilbur Ross, who appears to have the lead in crafting broader trade policy, along with Peter Navarro, head of the newly created White House National Trade Council, to “develop and implement trade policies that shrink our trade deficit, expand economic growth, strengthen our manufacturing base and help stop the exodus of jobs from our shores,” Trump’s communications office said.

There is still some question about the significance of Lighthizer’s role in a Trump administration, in light of Trump’s antitrade rhetoric on the campaign trail. He will succeed USTR Michael Froman, who as President Obama’s trade chief pursued several market-opening trade deals.

Trump vowed to withdraw the U.S. from the 12-nation Trans-Pacific Partnership on his first day in office and renegotiate the North American Free Trade Agreement between Mexico and Canada. He has also said he will impose tariffs of up to 45 percent on Chinese imports and 35 percent on Mexican imports and separately impose a 35 percent tariff on imports from companies that move offshore.

While some of Trump’s cabinet secretary designees have indicated they are open to negotiating smaller bilateral trade pacts, the tone on trade remains more of an enforcement-driven policy than a trade liberalizing one.

China also appears to be in the new administration’s crosshairs. Trump has said he will label China a currency manipulator in his first 100 days in office and go after unfair trade practices that have created a steep trade deficit with China.

Both Lighthizer and Navarro have been critical of China.

Trump touted Lighthizer’s experience in the trade arena, noting he has served in the legislative branch, executive branch and the private sector.

In addition to his role as deputy USTR under Reagan, Lighthizer served as chief of staff of the Senate Finance Committee that passed Reagan’s tax and spending cut proposals and helped in the passage of legislation that implemented the Tokyo Round of trade negotiations.

He has also represented the U.S. at meetings of the Organization for Economic Cooperation and Development as well as at meeting at the General Agreement on Tariffs and Trade, which preceded the World Trade Organization.

Lighthizer has been in charge of the international trade law practice at Skadden, Arps Slate, Meagher and Flom for over three decades.

While there he represented U.S. manufacturers in significant trade cases over the last 25 years, including the key steel safeguard case in the early Aughts under then President George W. Bush.

“He has worked on scores of successful cases that resulted in reducing unfair imports and helping thousands of American workers and numerous businesses,” according to the transition team.