Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Who's the poll source that claimed the Lead Margin was 17 and the Democrat: Jay Nixon had 54% of the votes?

### Inputs:
table_name: table, columns: ['Poll Source', 'Dates administered', 'Democrat: Jay Nixon', 'Republican: Kenny Hulshof', 'Lead Margin']

### Response:
SELECT Poll Source FROM table WHERE Democrat: Jay Nixon = 54% AND Lead Margin = 17