CREATE TABLE table_44558 ("Poll Source" TEXT, "Dates administered" TEXT, "Democrat: Carl Levin" TEXT, "Republican: Jack Hoogendyk" TEXT, "Lead Margin" FLOAT)

What is Poll Source, when Democrat: Carl Levin is 61%?
SELECT "Poll Source" FROM table_44558 WHERE "Democrat: Carl Levin" = '61%'
SELECT "Poll Source" FROM "table_44558" WHERE "Democrat: Carl Levin" = '61%'