Conventions were often heated affairs , playing a vital role in deciding each party 's nominee . The process remained far from democratic or transparent , however . The party convention was a scene of intrigue among political bosses , who appointed and otherwise controlled nearly all of the delegates . Winning a nomination involved intensive negotiations and multiple votes ; the 1924 Democratic National Convention required a record 103 ballots to nominate John W. Davis . The term " dark horse candidate " was coined at the 1844 Democratic National Convention , at which little-known Tennessee politician James K. Polk emerged as the candidate after the failure of the leading candidates — former President Martin Van Buren and Senator Lewis Cass — to secure the necessary two-thirds majority
1924 Democratic National Convention
1924 Democratic National Convention
United States presidential nominating convention