Some of the nation’s religious and socially conservative leaders are gathering in Washington this weekend for the Values Voter Summit, which includes a panel discussion on “The Future of Marriage.” This is the first time the group has met since the U.S. Supreme Court overturned a key provision in the federal Defense of Marriage Act that prevented legally wed same-sex couples from receiving all the federal benefits currently available to married couples of the opposite sex.

Support for same-sex marriage has been growing in recent years, with half (50%) of Americans now in favor and 43% opposed. While support is considerably lower among those who identify as white evangelical Protestant, Republican or politically conservative, support for same-sex marriage has risen even among these groups over the past decade, according to aggregated Pew Research data.

Today, roughly three-in-ten Republicans (29%) and political conservatives (30%) say they support same-sex marriage, compared with 12 years ago, when 21% of Republicans and 18% of conservatives expressed this view. About a quarter (23%) of white evangelical Protestants now say they favor same-sex marriage, compared with 13% in 2001.

Some of this shift in opinion is attributable to members of the Millennial generation (those born since 1980), who express higher levels of support for same-sex marriage than older age groups.

For example, data from Pew Research surveys from March and May 2013 show that adults under age 30 who say they are Republican or lean Republican are much more supportive of same-sex marriage (54%) than Republicans 65 and older (18%). At the same time, younger Republicans are much less supportive of same-sex marriage than those in the 18-29 age bracket who are Democrats or lean Democratic (54% vs. 76%).