Arkansas Sen. Mark Pryor is in a shrinking group of Democratic senators who haven't announced their support for gay marriage.
Two freshman Democratic senators, Joe Donnelly of Indiana and Heidi Heitkamp of North Dakota, said Friday that they support gay marriage.
So far, 49 Democrats, two independents and two Republicans have announced their support for gay marriage.
There are now only four Democrats in the Senate who have not expressed support for gay marriage: Pryor, Mary Landrieu of Louisiana, Tim Johnson of South Dakota, and Joe Manchin, of West Virginia.
Two Republican Senators, Mark Kirk of Illinois and Rob Portman of Ohio, have announced their support for gay marriage.