To forestall constitutional uncertainty, Tyler took the presidential oath of office on April 6, moved into the White House, and assumed full presidential powers, a precedent that would govern future extraordinary successions and eventually become codified in the Twenty-fifth Amendment. Tyler had more success in international affairs. During his last two years in office Tyler pressed for the annexation of Texas as a slave state, injecting the annexation issue into the 1844 presidential election. Expecting few responsibilities, he then left Washington, quietly returning to his home in Williamsburg. After his inauguration, Harrison called for a special session of Congress, to begin in late May, in order to address the dangerous financial condition of a country still in the midst of the Panic of 1837. The first few weeks of the presidency took a toll on Harrison's health, and after being caught in a rainstorm in late March he came down with pneumonia and pleurisy.