In the Democratic Party of the United States , the determination of a presidential nominee once required the votes of two-thirds of delegates to the Democratic National Convention . This rule was adopted in the party 's first presidential nominating convention — the 1832 Democratic National Convention . The two-thirds rule gave southern Democrats an effective veto over any presidential nominee for many years , until the rule 's abolition at the 1936 Democratic National Convention
1936 Democratic National Convention
1936 Democratic National Convention
Supermajority