user: Question: What was the lead margin when Nixon had 48% and reporting was done by rasmussen reports?
Columns: ['Poll Source', 'Dates administered', 'Democrat: Jay Nixon', 'Republican: Kenny Hulshof', 'Lead Margin']
Types: ['text', 'text', 'text', 'text', 'real']
Sample row: ['Public Policy Polling', 'November 2, 2008', '57.9%', '38.4%', 19.5]
SQL:

assistant: SELECT "Lead Margin" FROM "Table" WHERE "Democrat: Jay Nixon" = '48%' AND "Poll Source" = 'rasmussen reports';