A growing number of Republicans are breaking with the party's traditional stance to publicly state their support for same-sex marriage, a shift strategists say stems as much from demographics as from the renewed focus on economics and the "tea party" movement. A solid majority of adults younger than 30 - about six in 10 - support the right of gay and lesbian couples to legally wed, according to a Washington Post poll in February. But even many older Americans and self-identified social conservatives have changed their view on an issue that just six years ago galvanized voters in support of...