Table: gubernatorial_polls_2008
Columns: poll_source
dates_administered
democrat_jill_long_thompson
republican_mitch_daniels
lead_margin

Question: What is the lowest Lead Margin when Republican: Mitch Daniels was polling at 48%?
SQL: SELECT MIN("lead_margin") FROM gubernatorial_polls_2008 WHERE "republican_mitch_daniels" = '48%'