Actually, they should do both. But, when they do say NO, it must not be a policy wonk NO< It must be explained in a communicative way unlike the Bushies and insiders and explain the differences in easy to understand libertarian words. That way, the nation sees the differences and there still are some. Freedom is not in the Dem’s playbook. So, let the words battle begin with the best communicators from the GOP and make them young, attractive and high flyers not stodgy old timers.
For example, there is a compelling national interest to provide marital benefits to a spouse who is the primary care giver in a monogamous relationship, even after the children are raised and out on their own. On the other hand, there is no compelling national interest to provide marital benefits to an unemployed homosexual waiter who spends years not raising children. (There are numerous other examples of that, but I don't want to spend too much time writing an entire philosophy.)
Just as there is no compelling national interest to continue to spend money that we don't have. Eventually, somebody has to produce a budget and spending plan that at least levels off the national debt, even if there is no realistic way to reduce it significantly.
Just as there is no compelling national interest in providing benefits to illegal aliens who come to this country in violation of our laws. And so on.
This is not intended to lower the value of religious or moral objections to homosexual marriage, but to provide another vantage point. Logic may not produce the best sound bite, but it can provide a solid basis for arguments. We need to avoid demonization of people we don't agree with, and speak from the mind as well as the heart.