Rob Portman changed his mind and many GOP leaders would just as soon change the subject. But socially conservative Republican National Committee members gathering in one of the most gay-friendly places in the country are pushing the party to redouble its opposition to gay marriage. They may well succeed. Republican National Committee members here for their spring meeting are set to vote Friday on a resolution reaffirming the party’s official position that marriage should be solely between one man and one woman. It is expected to pass overwhelmingly.