Arnold Schwarzenegger is set to veto a bill allowing gay marriage in California. The Republican governor says he has no option but to reject it in the light of a state-wide referendum five years ago which saw voters define marriage as between a man and a woman. Democrats in the state legislature had suspected their celebrations would be short lived.Schwarzenegger, whose popularity has slumped in recent months, argues the gay marriage issue should be settled by the courts, or in another referendum. The issue has been on the agenda since last year, when the mayor of San Francisco allowed same-sex couples to tie the knot. Their marriage licences were invalidated by the California Supreme Court soon afterwards. Schwarzenegger says he believe gay couples are entitled to full legal protection and should not face discrimination.