The Democratic party's stance on gay marriage is, for all intents and purposes, the majority of the country's stance on gay marriage. Crucially, the Post poll shows that an even larger share of political moderates (55 percent) say that the Democratic position is closer to their own. Conservatives offered many ominous warnings about what would happen if gay marriage became the law of the land, but as more states have legalized it we have not seen much of an impact, except on the lives of people who love each other but couldn't previously have that bond legally recognized. Moreover, arguments against same-sex marriage have repeatedly been undermined by the courts, by conservative and liberal justices alike.
Republican candidates who continue to toe a hardline anti-gay marriage line may be at risk of losing credibility among a growing proportion of voters. But they may still need to appease the more vocal conservative elements of their base, who continue to agitate against same sex marriage. The safest stance for Republican candidates, then, is silence.