CREATE TABLE table_18343 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

How many incumbents resulted in a lost renomination republican gain?
SELECT COUNT("Incumbent") FROM table_18343 WHERE "Result" = 'Lost renomination Republican gain'
SELECT COUNT("Incumbent") FROM "table_18343" WHERE "Result" = 'Lost renomination Republican gain'