Final answer:
Calvin Coolidge chose not to run for reelection in 1928 and supported Herbert Hoover to run instead. He made this decision to continue the policies of prosperity and laissez-faire governance that were associated with the Republican Party.
Step-by-step explanation:
Calvin Coolidge chose not to run for reelection in 1928 because he announced, 'I choose not to run.' Instead, he supported his vice president, Herbert Hoover, to run for president. Coolidge's decision was influenced by the desire to continue the policies of economic prosperity and laissez-faire governance associated with the Republican Party at that time.