CREATE TABLE table_44627 ("Poll Source" TEXT, "Sample Size" FLOAT, "Margin of Error" FLOAT, "Date" TEXT, "Democrat" TEXT, "Republican" TEXT)

What is the date that the polls were going on at quinnipiac when john mccain was the republican, barack obama was the democrat and the sample size was bigger than 1427?
SELECT "Date" FROM table_44627 WHERE "Republican" = 'john mccain' AND "Poll Source" = 'quinnipiac' AND "Democrat" = 'barack obama' AND "Sample Size" > '1427'
SELECT "Date" FROM "table_44627" WHERE "Democrat" = 'barack obama' AND "Poll Source" = 'quinnipiac' AND "Republican" = 'john mccain' AND "Sample Size" > '1427'