Former President Donald Trump’s top trade policy adviser during his presidency has endorsed David McCormick for U.S. Senate in Pennsylvania, Breitbart News has learned exclusively.

The endorsement from Robert Lighthizer, provided exclusively to Breitbart News ahead of its public release, may be the biggest endorsement yet in the contentious U.S. Senate primary in Pennsylvania, and is a huge coup for McCormick who has been running a campaign focused on a populist nationalist vision on trade and immigration much like Trump’s insurgent 2016 presidential campaign.

Lighthizer served as Trump’s United States Trade Representative (USTR) and helped the then-president negotiate out historic deals like the landmark U.S.-Canada-Mexico (USMCA) agreement that eliminated and replaced the failed North American Free Trade Agreement (NAFTA). Lighthizer was also crucial to Trump’s efforts to crack down on the Chinese Communist Party, using tariffs and other trade policy mechanisms leading to Trump being the first president in decades to get tough on China after presidents of both parties had been cozying up to the CCP.

“It was the honor of a lifetime to oversee trade policy for the United States under President Trump,” Lighthizer said in the statement. “I know America First when I see America First and Dave McCormick is America First. From his military service to his business experience, Dave has the skill set, the devotion and the principles to take on China, take on Wall Street, take on the corrupt special interests and fight to keep our jobs and wealth at home. He will be a staunch supporter of the Trump administration’s successful worker-oriented trade policies and aggressive actions to counter China, including maintaining the Trump tariffs.”

File/U.S. Trade Representative Robert Lighthizer testifies during a House Ways and Means Committee hearing on February 27, 2019 in Washington, DC. The committee heard testimony regarding U.S.- China trade. (Mark Wilson/Getty Images)

Lighthizer continued by noting that he has spent his entire life fighting to keep jobs in America—and especially in Pennsylvania—and that McCormick in his view is the candidate in the Pennsylvania race that understand these issues and will actually do something about it.

“I fought to keep American manufacturing jobs in both the Reagan and Trump administrations and I fought to keep steel jobs in Pennsylvania and America for more than 35 years in my law practice,” Lighthizer said. “Dave understands the importance of these issues and has the backbone to take on those who get rich offshoring and outsourcing. He shares my passion for promoting American manufacturing, American supply chains, American energy and American self-sufficiency. Pennsylvania needs and deserves a Senator who will prioritize Pennsylvania workers, values and industry — and Dave is exactly that leader. He will be China’s worst nightmare and Pennsylvania’s greatest champion. It is my honor to formally endorse Dave for the United States Senate.”

McCormick celebrated the endorsement, adding in a statement of his own to Breitbart News that he thanks Lighthizer for it and for his work protecting American jobs from hostile foreign interests.

“It is a true honor to have the support of Ambassador Robert Lighthizer, someone who has worked on behalf of American workers at the highest levels of government,” McCormick said. “Under President Trump, Ambassador Lighthizer went head-to-head with China in negotiations for America First trade deals that were tough on China and fair to our workers and businesses here at home. I’m pleased Ambassdor Lighthizer recognizes our shared commitment to American industries and employees in Pennsylvania, combating China’s growing economic and military influence by moving critical supply chains and manufacturing jobs back to Pennsylvania; protecting US jobs and intellectual property; and continuing the fair trade policies successfully negotiated and implemented by Ambassador Lighthizer and President Trump. Ambassador Lighthizer has been crucial to countering China and I am proud to stand with him in this fight.”

David McCormick: “It is a true honor to have the support of Ambassador Robert Lighthizer, someone who has worked on behalf of American workers at the highest levels of government.”

This latest endorsement comes after several other major ones that have broken for McCormick in recent months. Everyone from former Secretary of State Mike Pompeo to Sen. Ted Cruz (R-TX) to House GOP conference chairwoman Rep. Elise Stefanik (R-NY) and more have endorsed McCormick. On McCormick’s campaign are several former top Trump aides like Hope Hicks and Cliff Sims, among others.

McCormick’s chief rival in the GOP primary for U.S. Senate in Pennsylvania is celebrity television doctor Mehmet Oz. Oz, who has a history of liberal positions, was born in Ohio to Turkish parents and maintains dual citizenship. He served in the military–of Turkey, not the U.S.–in order to maintain his Turkish citizenship. Oz now claims he will if elected to the U.S. Senate renounce his Turkish citizenship, but continues to refuse to do so until after the election and says he will only do it if he wins—a promise which only came after Oz was repeatedly criticized including by Sen. Dan Sullivan (R-AK) among many others for what the Washington Post said would be an unprecedented arrangement if elected.

Oz has a history of leftist positions on everything from immigration to the Second Amendment to healthcare to China to abortion to transgenderism and has come under major scrutiny during this primary. Oz’s history of being friendly with people like Oprah Winfrey and other top Hollywood liberals continues to be a centerpiece of criticism against him as well. Oz has responded by lashing out repeatedly, including most recently falsely claiming this publication gets paid for news stories about him and McCormick.

“Well, Breitbart, as you know, is having a lot of internal issues, financial issues,” Oz said in an interview this week. “They basically sell the articles now. So, I didn’t want to do that. I don’t want to buy articles.”

Oz’s claim, of course, is false. But the fact he is saying it would seem to be a sign his campaign is reeling from increased news exposure.

While McCormick keeps racking up actual quality endorsements and focusing on core policy solutions on issues like trade and immigration—he recently visited the border where the National Border Patrol Council backed him, just like the union of Border Patrol agents did with Trump in 2016—Oz only has Fox News host Sean Hannity on his side. Hannity keeps telling Pennsylvanians to trust him about Oz.