Since President Obama publicly stated that he personally supports same-sex marriage, we have seen support grow at both the national and state level. While support has grown among most groups, much of the growth has come from Obama’s biggest supporters, African-Americans. From PPP:

Pennsylvania voters still oppose gay marriage but they have moved by 7 points on the issue since PPP polled the state in November. 39% support it to 48% opposed. That 9 point margin is down from 16 points at 36/52 last fall. The most notable movement over that period of time has come with African Americans. They now narrowly support gay marriage, 42/41, after previously opposing it by a 52/34 margin.

We’ve seen that kind of dramatic movement with black voters in North Carolina as well. While the media has been very focused on the question of how Barack Obama’s announcement on gay marriage will affect his own reelection prospects (not much) the bigger question might be how it’s going to affect overall public opinion on gay marriage. The answer so far- at least with black voters- is quite a bit.

Given the demographic breakdown, support for marriage equality was destined to grow regardless of what Obama did.  But his public endorsement helped to accelerate the trend. He brought attention to the issue, which caused some including many of his biggest supporters to re-examine their opinions on the matter.

The bully pulpit is not some magic device that can reshape politics on every issue, but it is a real tool of the president that can be quite powerful in particular circumstances. Whether the issue is the build up to the war in Iraq, bombing Libya or marriage equality, a president and his administration speaking out forcefully for something can really shape popular opinion, especially among the president’s base.