The poll source when Democrat Carl Levin had 54% and the lead margin was 28 was epic-mra.
[['September 14-September 17, 2008', 'POLL_SOURCE', 'EPIC-MRA'], ['September 14-September 17, 2008', 'LEAD_MARGIN', '28'], ['September 14-September 17, 2008', 'DEMOCRAT:_CARL_LEVIN', '54%']]