user: Question: What is the largest lead margin when Schweitzer has 55% and Jones is not an option?
Columns: ['Poll Source', 'Dates administered', 'Democrat: Brian Schweitzer', 'Republican: Roy Brown', 'Libertarian: Stan Jones', 'Lead Margin']
Types: ['text', 'text', 'text', 'text', 'text', 'real']
Sample row: ['Public Policy Polling', 'November 2, 2008', '62%', '36%', 'not an option', 26.0]
SQL:

assistant: SELECT MAX("Lead Margin") FROM "Table" WHERE "Democrat: Brian Schweitzer" = '55%' AND "Libertarian: Stan Jones" = 'not an option';