Support for gay marriage among Democrats has increased 15 percent since 2008, a new The Pew Forum on Religion & Public Life survey has found.

According to the nationwide poll of 2,973 adults conducted between June 28 – July 9, 65 percent of Democrats support gay nuptials, while 29 remain opposed. That's a 15 percent increase since 2008 when Democrats were more evenly divided on the issue (50-42%), and a 25 percent rise since 2004.

Republican support for the institution has also grown, but at a more modest pace. In 2008, 19 percent of Republicans said they favored the institution. Four years later, that number has increased 5 percent. A large majority (70%) of Republicans oppose such unions.

Independents are more divided on the issue. Fifty-one percent are in favor and 40 percent against, an increase of 7 percent since 2008.

Pollsters concluded that President Barack Obama's May announcement in support of gay marriage has had little effect on public opinion.

However, the president's opinion may have rallied Democrats to the issue. A six percent gain in support was seen among Democrats after the president's announcement.

The percentage of Americans who believe being gay is a choice has remained relatively unchanged over the past six years, moving from 39 percent in 2006 to 36 percent today.