The Washington Post's Aaron Blake on one of the many reasons why polls claiming majority support for SSM don't reflect reality -- they don't offer all the options:

"...One Republican pollster said support for gay marriage has been oversold because of that binary choice. The pollster asked for anonymity to candidly discuss a sensitive issue.

“For the most part, the polling out there is combining the civil union and gay marriage responses together to get their ‘majority’ supporting gay marriage,” said the pollster. “There’s a reason why the (gay marriage) ban has passed in 32 states, and there’s a reason the gay community is starting to go through the legislative process.”

... “When we give voters the easier choice [civil unions], they frequently take it. Civil unions is an easier choice,” said one Democratic pollster, who also asked for anonymity because if the issue’s sensitivity. “It’s why, for example, most pollsters don’t read people ‘undecided’ as an option when asking people a head to head. If you read people an ‘undecided’ choice, they are always more apt to take the out.”