1848 Democratic National Convention

• 
  Senator
  Lewis Cass
  of Michigan
• 
  Associate Justice
  Levi Woodbury
  of New Hampshire
• 
  Secretary of State
  James Buchanan
  of Pennsylvania
• 
  Former President
  Martin Van Buren
  from New York
  (withdrew before first ballot)

• 
  Senator
  William Allen
  of Ohio
  (Endorsed Cass)

The main competitors for the nomination were Senator Lewis Cass of Michigan, Secretary of State James Buchanan from Pennsylvania, and Supreme Court Justice Levi Woodbury from New Hampshire. Former President Martin Van Buren also desired to become the Democratic Party's candidate in the 1848 election. Some party leaders asked William Allen to enter the contest as a compromise candidate, but he refused to run for the presidency. Instead, Allen chose to support Cass over Van Buren due to the two men's mutual support of popular sovereignty.

Van Buren withdrew before balloting began due to a dispute over the seating of the New York delegation that culminated in the convention voting that half of the state's delegates be made up of the anti-slavery "Barnburner" faction, led by Van Buren, with the remaining half from the pro-slavery "Hunker" faction.

Van Buren, knowing he had no feasible path to winning the nomination without the full support of the New York delegation, promptly led the Barnburners in walking out of the convention. Bitter and aging, Van Buren did not care despite the fact that his life had been built upon the rock of party solidarity and party regularity. He loathed Lewis Cass and the principle of popular sovereignty with equal intensity.[5] After it was further ruled the Hunkers would not be allowed to take the vacated seats of their absent Barnburner counterparts, they cast blank ballots during the voting.

On the first ballot, Cass had a large lead with 125 of the 254 delegate votes cast, with Buchanan and Woodbury receiving 55 and 53 votes respectively.[1] On the next two ballots Cass gained a simple majority, while Woodbury's total was steady and Buchanan's began to fall. After Cass received 179 votes out of 254 on the fourth ballot, the chair declared that Cass had reached the required 170 votes and was therefore nominated.

• 
  1st Presidential Ballot
• 
  2nd Presidential Ballot
• 
  3rd Presidential Ballot
• 
  4th Presidential Ballot

• 
  Former Representative
  William O. Butler
  of Kentucky
• 
  Former Governor
  John A. Quitman
  of Mississippi
• 
  Former Senator
  William R. King
  of Alabama
• 
  Secretary of the Navy
  John Y. Mason
  of Virginia
• 
  Representative
  James Iver McKay
  of North Carolina
• 
  Inspector General of the Tennessee Militias
  Levin Hudson Coe
  of Tennessee[6]

• 
  Reporter of Decisions
  Benjamin Howard
  of Maryland

Cass/Butler campaign poster

Turning to the choice of a vice presidential running mate, the convention picked General William O. Butler of Kentucky[1] over General John A. Quitman of Mississippi, former Senator and Minister to France William R. King of Alabama, Secretary of the Navy John Y. Mason of Virginia, and Representative James Iver McKay of North Carolina. Before it adjourned on May 25, this convention also appointed the first Democratic National Committee.[1]

• 
  1st Vice Presidential Ballot
• 
  2nd Vice Presidential Ballot Before Shifts
• 
  2nd Vice Presidential Ballot After Shifts