Since Howard Lutnick was tapped to serve as President Trump’s commerce secretary, executives from some of the world’s largest companies have been trying to win him over.

Leaders of Nvidia, Facebook, Taiwan Semiconductor Manufacturing Company and Alphabet have visited his newly purchased $25 million property in Washington — a 16,250-square-foot mansion that Mr. Lutnick, a billionaire, recently quipped would be “big enough for my ego” — to persuade him to adopt a business-friendly agenda.

As Mr. Trump ratcheted up tariffs to levels not seen in a century, Ford, General Motors and other companies that have built their businesses around international trade reached out to Mr. Lutnick in the hope that he could persuade the president to take a less aggressive approach. Some chief executives have put in calls to the commerce secretary at midnight.

Mr. Lutnick, 63, heads a department that both promotes and regulates industry and he has been put in charge of overseeing trade. As a result, he has found himself in a position of incredible influence, as the go-between for a president imposing sweeping tariffs and the industries being crushed by them.

A former bond trader who amassed billions on Wall Street, Mr. Lutnick has become one of the loudest salesmen for tariffs in an administration generally unified on their benefits. He has publicly echoed the president’s message that big tariffs are needed to revive American industry, and that if companies don’t like them, they should build factories in the United States.

But in internal conversations in the administration, he has often been a voice for moderation. He argued in favor of Mr. Trump pausing his global tariffs for 90 days after they sent convulsions through the stock and bond markets. And he has made the case to the president to grant relief to certain favored industries, helping them to win exemptions from billions of dollars of levies.