The Mexican political system was again seen as fragile when in 1928 a religious fanatic assassinated president-elect Obregón, who would have returned to the presidency after a four-year hiatus. Calles stepped in to form in 1929 the "Partido Nacional Revolucionario", the precursor to the Institutional Revolutionary Party, helped stabilize the political and economic system, creating a mechanism to manage conflicts and set the stage for more orderly presidential elections. Later that year, the U.S. stock market crashed and the Mexican economy suffered as the worldwide Great Depression took hold. It had already slowed in the 1920s, with investor pessimism and the fall of Mexican exports as well as capital flight. Even before the Great Crash of the U.S. stock market in 1929, Mexican export incomes fell between 1926 and 1928 from $334 million to $299 million (approximately 10%) and then fell even further as the Depression took hold, essentially collapsing. In 1932, GDP dropped 16%, after drops in 1927 of 5.9%, in 1928 5.4%, and 7.7%, such that there was a drop in GDP of 30.9% in a six-year period.