CREATE TABLE table_21785 ("Poll Source" CLOB, "Dates administered" CLOB, "Democrat: John Lynch" CLOB, "Republican: Joe Kenney" CLOB, "Lead Margin" FLOAT)

Name the number of lead margin for republican joe kenney being 31%
SELECT COUNT("Lead Margin") FROM table_21785 WHERE "Republican: Joe Kenney" = '31%'
SELECT COUNT("Lead Margin") FROM "table_21785" WHERE "Republican: Joe Kenney" = '31%'