WASHINGTON — For three years, Peter Navarro has been corporate America’s biggest nemesis, punishing multinational companies for moving jobs offshore by advocating tariffs and other trade barriers in pursuit of President Trump’s “America First” strategy.

Now, as the United States scrambles to secure equipment to fight the coronavirus, Mr. Navarro has been handed expansive authority over those multinational firms and their global supply chains.

As the policy coordinator for the Defense Production Act, a Korean War-era law that the president recently invoked, Mr. Navarro is tasked with marshaling American industry to procure face masks, ventilators and other products hospitals need in their fight against the coronavirus. He has been given the authority to order up products, block exports and claim goods made overseas by subsidiaries of American companies. He can also seize products from hoarders and price gougers and channel them to where they are most needed.

It is a vast expansion of power for the 70-year-old Mr. Navarro, as well as a rare opportunity to advance the type of protectionist agenda that has endeared him to Mr. Trump. A Harvard-trained economist whose ideas put him at odds with most of his profession, Mr. Navarro has antagonized multinational companies by pushing to scrap trade deals and impose tariffs on foreign products. He is now positioned to channel government resources into bolstering American manufacturing and to bully multinational companies to sever their ties abroad.