But while same-sex marriage is gaining ground, another key Democratic social issue — abortion rights — is losing support. A majority of those surveyed - 52 percent - said they think abortion should be either completely outlawed or only allowed under certain exceptions, like in the case of rape or incest. By contrast, 45 percent said abortion should be legal "always" or "most of the time."

In a similar poll in January, a majority for the first time said they believed abortion should be legal "always" or "most of the time."

Given that split, it is perhaps unsurprising that parties earn low marks when it comes to their handling of social issues. Only 22 percent of respondents say they agree with the Republican approach on cultural issues, while 37 percent say they agree with Democrats. By contrast, 47 percent say they actively oppose the Republican approach to social issues, and 38 percent say the same of Democrats.