Poll analyzing wunderkind Nate Silver looks at the numbers for his New York Times blog:
A poll from CNN this week is the latest to show a majority of Americans in favor of same-sex marriage, with 51 percent saying that marriages between gay and lesbian couples “should be recognized by the law as valid” and 47 percent opposed.
This is the fourth credible poll in the past eight months to show an outright majority of Americans in favor of gay marriage. That represents quite a lot of progress for supporters of same-sex marriage. Prior to last year, there had been just one survey — a Washington Post poll conducted in April 2009 — to show support for gay marriage as the plurality position, and none had shown it with a majority.
The change — about a 4 percentage-point shift in favor of gay marriage in each of the last two years — is about double the longer-term rate of progress for supporters of gay marriage, which has been between 1 and 2 percentage points per year.
There is a margin of error associated with the calculation of the trendline, so it is too soon to say with confidence that support for gay marriage has become the plurality position (let alone the majority one). Other polls — like a Pew survey released in March — continue to show opinion split about evenly.
However, opponents of gay marriage almost certainly no longer constitute a majority; just one of the last nine polls has shown opposition to gay marriage above 50 percent.