Republicans in battleground districts have a tricky path to walk. They must gain support from their base of conservatives who are opposed to marriage equality but not reject the moderate voters who support it. They must also consider the moderate voters who support equality and who the candidate will need in a general election.
Bruce Gyory, a political consultant to Democratic and Republican governors who studies voter trends, said opposition to marriage equality in New York will hurt a Republican in the general election.
In Maryland and Washington state, public votes on gay marriage are scheduled for this fall while voters in Maine also will address the issue in November, three years after a referendum overturned a gay marriage law passed by the state Legislature.
Same-sex marriage is legal in New York, Vermont, New Hampshire, Connecticut, Iowa, Massachusetts and Washington, D.C.