WASHINGTON—Howard Lutnick’s journey from Wall Street veteran to one of President Trump’s most hawkish trade advisers began with a speech at his October campaign rally at Madison Square Garden. Lutnick extolled the virtues of tariffs and argued that the duties could at least in part replace the U.

Howard Lutnick, President Donald Trump’s nominee to lead the Commerce Department, offered a detailed defense of tariffs in his confirmation hearing, the clearest signal yet from a cabinet pick that the new administration is prepared to impose the levies on allies and adversaries alike.