CREATE TABLE table_21036 ("Poll Source" TEXT, "Dates administered" TEXT, "Democrat: Dick Durbin" TEXT, "Republican: Steve Sauerberg" TEXT, "Lead Margin" FLOAT)

Name the republican steve sauerberg where dates administered september 15-september 18, 2008
SELECT "Republican: Steve Sauerberg" FROM table_21036 WHERE "Dates administered" = 'September 15-September 18, 2008'
SELECT "Republican: Steve Sauerberg" FROM "table_21036" WHERE "Dates administered" = 'September 15-September 18, 2008'