user: Question: What were the dates administered when the lead margin was smaller than 39 with Republican Christopher Reed at 37% and Democrat Tom Harkin at 53%?
Columns: ['Poll Source', 'Dates administered', 'Democrat: Tom Harkin', 'Republican: Christopher Reed', 'Lead Margin']
Types: ['text', 'text', 'text', 'text', 'real']
Sample row: ['Survey USA', 'October 28-October 29, 2008', '61%', '35%', 26.0]
SQL:

assistant: SELECT "Dates administered" FROM "Table" WHERE "Lead Margin" < 39.0 AND "Republican: Christopher Reed" = '37%' AND "Democrat: Tom Harkin" = '53%';