In the summer of 1927, Coolidge vacationed in the Black Hills of South Dakota, where he spent time horseback riding and fly fishing. He attended rodeos and dubbed Custer State Park as his "summer White House". While on vacation, Coolidge surprised everyone with an announcement, one that he hadn't even discussed with his wife. Coolidge issued a terse, Coolidge-esque statement, announcing that he would not seek a second full term as president. The statement simply began: "I do not choose to run for President in 1928." After allowing the reporters who were covering his vacation to take that in, Coolidge explained himself. He said, "If I take another term, I will be in the White House till 1933", adding, "Ten years in Washington is longer than any other man has had it—too long!"
In his memoirs, Coolidge explained his decision not to run: "The Presidential office takes a heavy toll of those who occupy it and those who are dear to them. While we should not refuse to spend and be spent in the service of our country, it is hazardous to attempt what we feel is beyond our strength to accomplish."
Four years earlier, on July 7, 1924 his 16 year old son Calvin Jr. died unexpectedly after a blister he had gotten playing tennis with his brother on the White House tennis courts became infected and developed into sepsis. Years later, when Calvin Coolidge wrote his autobiography, typical of him, he said little about the controversial subjects of his presidency. But there was one issue on which Calvin Coolidge let down his guard and provided some insight into his innermost thought, that being on the death of his son Calvin Jr. Of his son, Coolidge wrote:
"He was a boy of much promise, proficient in his studies, with a scholarly mind, who had just turned sixteen. He had a remarkable insight into things. The day I became president he had just started to work in a tobacco field. When one of his fellow laborers said to him 'If my father was President I would not work in a tobacco field', Calvin replied 'If my father were your father you would'... If I had not been President, he would not have raised a blister on his toe, which resulted in blood poisoning, playing tennis in the south grounds. In his suffering he was asking me to make him well. I could not. When he went, the power and the glory of the Presidency went with him. The ways of Providence are often beyond our understanding. It seemed to me that the world had need of the work that it was probable he could do. I do not know why such a price was exacted for occupying the White House... It costs a great deal to be President."
Coolidge's announcement might have left the party scrambling for new candidate, but at the time, there was almost no doubt who would succeed Coolidge. The rising star in the party was entrepreneur whiz kid Herbert Hoover. In 1920, President Warren Harding rewarded engineer Herbert Hoover for his support during the election. He offered to appoint Hoover as either Secretary of the Interior or Secretary of Commerce. Commerce was considered a minor Cabinet post, but Hoover decided to accept the position. Hoover's support for the League of Nations, and his recent conversion to the Republican Party created opposition to his appointment from many Senate Republicans at the time, but Harding paired Hoover's nomination with that of conservative Andrew Mellon as Secretary of the Treasury, and the nominations of both men were confirmed by the Senate.
Hoover would serve as Secretary of Commerce from 1921 to 1929, serving under both Harding and Coolidge. Although some of the most prominent members of the Harding administration were implicated in major scandals, Hoover emerged with his reputation unscathed. As Commerce Secretary, Hoover sought balance the interests of labor, capital, and government. He took on some of the responsibilities from other Cabinet departments and some began referring to him as the "Secretary of Commerce and Under-Secretary of all other departments." He also used the growing technology of radio to his advantage as the number of families with radios grew from 300,000 to 10 million between 1923 and 1929. Hoover played a key role in the organization and regulation of radio broadcasting.
Hoover built up support for a future presidential bid throughout the 1920s, but did so discretely because he was uncertain if Coolidge planned to run for another term in 1928. When Coolidge announced in August 1927 that he would not seek another term, Hoover immediately emerged as the front-runner for the 1928 Republican nomination. He put together a strong campaign team led by Hubert Work, Will H. Hays, and Reed Smoot.
Coolidge was not happy with the notion of Hoover becoming his successor. On one occasion he remarked that, "for six years that man has given me unsolicited advice; all of it bad." But Coolidge also did not want to split the party by publicly opposing Hoover's popular candidacy.
Many Republican leaders looked for an alternative candidate, such as Treasury Secretary Andrew Mellon or former Secretary of State Charles Evans Hughes. Hughes and Mellon declined to run. Other potential contenders included Illinois Governor Frank Lowden, Vice President Charles Dawes, Senators James Eli Watson of Indiana, Charles Curtis of Kansas, Guy D. Goff of West Virginia, and Frank Willis of Ohio. Lowden and Dawes failed to garner much support.
The 1928 National Convention of the Republican Party of the United States was held at Convention Hall in Kansas City, Missouri, from June 12 to June 15, 1928. The platform praised the Coolidge administration for the prosperity of the mid-1920s. It promised many things, including: reduction of the national debt, tax reduction, retention of the protective tariff, opposition to cancellation of foreign debts, settlement of claims from World War I from foreign governments, continuation of the Coolidge foreign policy, support of arbitration treaties, civil service protection, a tariff for agricultural protection and continued farm exports, aid to the coal-mining industry, continued appropriations for highway construction, the right to collective bargaining, regulation of railroads, a continued independent American merchant marine, government supervision of radio facilities, construction of waterways to help transportation of bulk goods, support for war veterans, federal regulation of public utilities, conservation, vigorous law enforcement, honest government, continued reclamation of arid lands in the West, improvement of air-mail service, restricted immigration and naturalization of foreign immigrants in America, continued enforcement of the Washington Naval Treaty, continued status of territory status for Alaska and Hawaii and called for more women in public service, right of the President to draft defense material resources and services, creation of an Indian Commission, an Anti-Lynching Law and promised continued Home-Rule for the American Citizen.
Hoover was distrusted by many Republicans because he had worked in the Wilson administration before the Harding, and Coolidge administrations. They also distrusted him on patronage. Progressive Republicans were split over Hoover. California Senator Hiram Johnson disliked Hoover, but Senator William E. Borah supported Hoover's candidacy. Some tried to convince Treasury Secretary Andrew Mellon to run for the nomination, but at 73, Mellon felt that he was too old to run in 1928. Mellon tried to convince former Secretary of State and 1916 Republican nominee Charles Evan Hughes to run, but Hughes refused to campaign for the nomination.
A "draft Coolidge" movement emerged, but the movement collapsed once Coolidge made it clear that he would not run again. With Coolidge out of the running, Senate Majority Leader Charles Curtis tried to rally Hoover's rivals around his own candidacy.
When voting began, Hoover won the nomination handily on the first ballot. He received 837 votes. No other candidate received more than 100. Lowden was closest with 74. Curtis received 64, and was selected as Hoover's running mate. Convention delegates considered re-nominating Vice President Charles Dawes to be Hoover's running mate, but relations between Coolidge and Dawes had soured, and Coolidge remarked that this would be "a personal affront" to him. Hoover accepted the nomination at Stanford Stadium, telling a huge crowd that he would continue the policies of the Harding and Coolidge administrations. The Democrats nominated New York governor Al Smith, who became the first Catholic major party nominee for president.
Hoover campaigned on the Republican record of peace and prosperity. His spin doctors promoted Hoover's reputation as a successful engineer and public official. Hoover disliked campaigning and let Curtis and other Republicans do the bulk of it. Smith was more personalble and gregarious than Hoover, but his campaign was damaged by anti-Catholicism and his opposition to Prohibition. Hoover was ambivalent on the issue and accepted the Republican Party's plank in favor of it. He issued a statement calling Prohibition "a great social and economic experiment, noble in motive and far-reaching in purpose." In the South, Hoover and the Republicans promoted a strategy that attempted to curry favor with white Southerners.
Hoover maintained his lead in the polls throughout the 1928 campaign. He soundly defeated Smith on election day, taking 58 percent of the popular vote and 444 of the 531 electoral votes. Hoover's national reputation and the booming economy contributed to his huge win, along with a split in the Democratic Party over religion and Prohibition. Hoover won five Southern states, breaking the Democratic grip on the south. One newspaper wrote that Hoover would "drive so forcefully at the tasks now before the nation that the end of his eight years as president will find us looking back on an era of prodigious achievement."