Most Americans oppose same-sex marriage. Most Americans support civil unions.
More than half the states have passed bans on same-sex marriage, most putting it right in the state constitution. Several of those states still offer civil unions.
Civil unions are popular -- especially with heterosexual couples. Same-sex marriage is rarely used even in those places where it is legal. A few states would legalize same-sex marriage through the legislature, not the court. More power to them, I say, and bless the great diversity of jurisdictions that these united States afford.
Civil unions deliver 90% of what the proponents of same-sex marriage want. For people who want to win, it is not just half-a-loaf, it is nearly the whole meal. The rest is mostly drama and symbolism.
President Obama, the supposed "most liberal member of the Senate" supports civil unions and opposes same-sex marriage. I am with "No-drama Obama." Take civil unions, declare victory, and let's get on with life.