Frequently mentioned as a presidential candidate for either of the major political parties in 1920, Hoover showed a qualified interest in the possibility. He had been a loyal Wilsonian, at least publicly, ardently championing the League of Nations. As vice chairman of the Second Industrial Conference (1919–1920), he had advanced the cause of collective bargaining for labor. He also denounced elements of the Red Scare. He announced that he was a Republican the same month. After Harding easily swept the election in a public repudiation of Wilson, the new president appointed Hoover to be secretary of commerce.
Hoover brought representatives of industry to Washington conferences to exchange information in order to improve efficiency and standardization. The representatives would agree on a "sense of the meeting" and return home to propagandize for their recommendations. The impetus the trade association movement received from Hoover's office was only temporarily dampened by Justice Department efforts to prevent price-fixing. When progressives protested that he was not using his office to promote business reform, he replied that the Commerce Department was not the appropriate agency. But Hoover had an important part in ending the twelve-hour day in the steel industry and winning the Jacksonville Agreement, which brought temporary labor peace to many of the soft-coal fields. Regulation of radio and the air-waves and the airplane industry also began under Hoover's Commerce Department.
Hoover increased fourfold the personnel of the Bureau of Foreign and Domestic Commerce, to promote a free-flowing international trade. The bureau increased United States business by hundreds of millions of dollars a year. Hoover particularly wanted commercial expansion to replace military adventurism, especially in Latin America. He took it as a matter of faith that an increased American commercial role abroad would bring a higher standard of living both to the United States and to the rest of the world. Through noncoercive means, he strove to divert American loans away from the support of armaments and risky investments.
That commitment to the spread of commerce as a means to a world free of war says a great deal about the mentality of Hoover: his trust in the rational, orderly mind and processes of modern industry and trade, his search for a workable combination of private economic activity and governmental planning, and his Quaker-like vision of an industrious, peaceful world. It must have seemed, in the sunny year when the former secretary of commerce assumed the presidency, that the planet was ready to be nudged into that future.
In the 1928 campaign, Hoover took a moderate course on the issue of Prohibition, promising a national commission on law observance to study what he cautiously termed "a great social and economic experiment noble in motive and far-reaching in purpose." Hoover respected the attempt at reform because it showed that "property rights did not dominate American ideals." But he also came to accept the belief that Prohibition had failed after being given an "honest trial." As president, he worked to enforce it, within the limits of law, because it was his duty to do so under the Constitution. Yet the report of his commission, which contained only one Prohibitionist, was evasive if not confused. Seven of its eleven members favored revision, but the report also called for a further trial at enforcement. "The findings are wet and the recommendations are dry," the despairing president complained to his secretary of state. Hoover remained the captive of the Prohibitionists through the 1932 campaign, and Roosevelt was the beneficiary of growing sentiments for repeal. The presidency would provide a test of Hoover's Quaker background and prowess as a social engineer.