Twenty-three percent of independent voters are less likely to vote for Barack Obama because of his announcement that he supports same-sex marriage, according to a Gallup/USA Today poll. Eleven percent are more likely. There might also be a slight shift in how Democrats and Republicans are inclined to vote: while only 2 percent of Republicans say that Obama’s decision makes them more likely to vote for him, 10 percent of Democrats say they’re less likely to back Obama.