less than a year ago in may 2012 joe biden publicly supported same-sex marriage on "meet the press." he was way out front. prompting the president to do the same just a few days later. then nevada senator, democratic leader harry reid the next day said he, too, thought gays should be able to marry legally. fast forward to the last month. we've seen an incredible swell of support. starting with rob portman in mid-march. citing his gay son the reason to re-evaluate his position. hillary clinton three days later taped a video for the human rights campaign endorsing same-sex marriage. then came senators mccaskill, rockefeller, tester, hagan, casey, carper, kirk, bill nelson, heitkamp, donnelly and today tim johnson. three have not backed it. louisiana's mary landrieu, arkansas' mark pryor and senator manchin. why does it seem to happen day after day after day? is it a big plus for democrats? >> it's a big plus for democrats. republicans have explaining to