Buchanan retired from politics after serving as secretary of state. He had sought the Democratic Presidential nomination again in 1848, when the nod went to Lewis Cass of Michigan. After Cass lost the presidential election to Whig candidate Zachary Taylor, Buchanan left Washington, D.C. and returned to his home in Lancaster. He purchased a large estate called Wheatland and reared his niece Harriet Lane, the orphaned daughter of his sister.