In the 2016 presidential campaign, Vermont Senator Bernie Sanders sought the Democratic Party's nomination in a field of six major candidates and was the runner up with 46% of the pledged delegates behind former Secretary of State Hillary Clinton, who won the contest with 54%. Sanders, the junior United States senator and former Representative from Vermont, began with an informal announcement on April 30, 2015, and a formal announcement that he planned to seek the Democratic Party's nomination for President of the United States on May 26, 2015, in Burlington, Vermont. Sanders had been considered a potential candidate for president since at least September 2014. Though he had previously run as an independent, he routinely caucused with the Democratic Party, as many of his views align with Democrats. Running as a Democrat made it easier to participate in debates and get his name on state ballots.

Presidential primaries and caucuses were organized by the Democratic Party to select the 4,051 delegates to the 2016 Democratic National Convention held July 25–28 and determine the nominee for president in the 2016 United States presidential election. The elections took place within all fifty U.S. states, the District of Columbia, five U.S. territories, and Democrats Abroad and occurred between February 1 and June 14, 2016.