A poll released on Thursday suggests that voters in the state of Maryland could be the first to approve equal marriage by a popular vote.
Figures released by the Washington Post, said that 52% of voters approved equal marriage, while 43% were opposed to the idea.
There are currently six states in which equal marriage is legal, however no state has ever legalised same-sex marriage through a referendum.
On 6 November voters in Maryland will decide whether to make equal marriage legal in the state.
This does not represent guaranteed success for equal marriage in Maryland, however, as historically polls such as this one have underestimated opposition to equal marriage.
The poll showed sharp divides between different race, age, political party and geographical locations. White voters and Democrats were more likely to vote in favour of the measure, while African American voters, who make up a large proportion of the electorate in Maryland polled slightly against it.
Voters in Maine and Washington will also vote on the same issue on 6 November. At the same time, Minnesota voters will choose whether to make a constitutional amendment which would define marriage as only between one man and one woman.